List of sets of four countries that border one another
[[Image:Enclave-of-Three.svg|right|thumb|Three countries surrounded by one other|figure 1]]
[[Image:Triclave.svg|right|thumb|One country surrounded by three others|figure 2]]
[[Image:Enclave-of-Two-within-Two.svg|right|thumb|Two countries surrounded by two others|figure 3]]
This is a list of sets of at least four countries that border one another. According to [[four colour theorem]], in [[Dimension|geometric 2d-space]], no more than four continuous two-dimensional [[shape]]s can all share one-dimensional [[Boundary|BOUNDARIES]] with each other. There are three ways this is possible: three shapes that border one another combining to form an [[enclave]] within the fourth (figure 1), a single shape forming an enclave within the combination of three shapes that border one another (figure 2), or two shapes enclaved within the combination of two others (figure 3).
Since, because of [[exclave]]s such as overseas territories, not all nations can be represented by single continuous two-dimensional shapes, the number of nations which can possibly share a border with each other is not necessarily limited to four.
==Current instances internationally==
In typical cases geographically, a set of four countries that border one another is formed when three nations that border one another form a ring around a landlocked fourth (which borders only the other three), as per figure 2. [[Paraguay]], [[Luxembourg]], [[Burundi]], and [[Malawi]] are examples of nations that are at the center of such configurations. However, the fact that a country may have [[exclave]]s and [[dependent territories]] CREATES other possibilities. As of the 2006 breakup of [[Serbia and Montenegro|the State Union of Serbia and Montenegro]], there are at least twelve four-nation sets in the world in which each nation shares a boundary (land or fresh water) with each other.
==South America==
===Paraguay-Brazil-Argentina-Bolivia===
[[Image:PAR-BOL-BRA-ARG.png|right|thumb|Map of Paraguay|'''Paraguay''' (red), '''Brazil''' (blue), '''Argentina''' (green), and '''Bolivia''' (magenta)]]
This set has existed since the early 19th century. In the 1800s all that existed was the Spanish [[Viceroyalty of the Río de la Plata]] and the Portuguese colony of [[Brazil]]. With the independence of [[Argentina]] (revolution in [[1810]], fully achieved [[1816]]) and [[Paraguay]] ([[1811]]) the four-border set began to emerge, and was consolidated by the Brazilian and [[Bolivia]]n independence ([[1822]] and [[1825]], respectively).
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Paraguay}} !! {{flagicon|Brazil}} !! {{flagicon|Argentina}} !! {{flagicon|Bolivia}}
|-
| '''{{flag|Paraguay}}''' ||align="center"| - || 1290 || 1880 || 750
|-
| '''{{flag|Brazil}}''' || 1290 ||align="center"| - || 1224 || 3400
|-
| '''{{flag|Argentina}}''' || 1880 || 1224 ||align="center"| - || 832
|-
| '''{{flag|Bolivia}}''' || 750 || 3400 || 832 ||align="center"| -
|}
==Eastern Europe==
===Belarus-Latvia-Lithuania-Russia===
This set has existed since the [[1991]] [[History of the Soviet Union (1985–1991)#Dissolution of the USSR|Dissolution of the Soviet Union]]. The Russian [[Kaliningrad Oblast]], an exclave on the [[Baltic Sea]], creates a [[Russia]]n border with [[Lithuania]]. [[Belarus]] and [[Latvia]] share boundaries with both mainland Russia and Lithuania.
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Belarus}} !! {{flagicon|Latvia}} !! {{flagicon|Lithuania}} !! {{flagicon|Russia}}
|-
| '''{{flag|Belarus}}''' ||align="center"| - || 171 || 502 || 959
|-
| '''{{flag|Latvia}}''' || 171 ||align="center"| - || 576 || 292
|-
| '''{{flag|Lithuania}}''' || 502 || 576 ||align="center"| - || 227
|-
| '''{{flag|Russia}}''' || 959 || 292 || 227 ||align="center"| -
|}
===Belarus-Lithuania-Poland-Russia===
[[Image:BLR-LTU-POL-RUS.png|right|thumb|Map of Belarus|'''Belarus''' (magenta), '''Lithuania''' (blue), '''Poland''' (green), and '''Russia''' (red)]]
This set has existed since the [[1991]] [[History of the Soviet Union (1985–1991)#Dissolution of the USSR|Dissolution of the Soviet Union]].
The Russian [[Kaliningrad Oblast]], an exclave on the [[Baltic Sea]], creates [[Russia]]n borders with both [[Lithuania]] and [[Poland]]. [[Belarus]] does not border Kaliningrad, but has borders with mainland Russia, Lithuania, and Poland.
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Belarus}} !! {{flagicon|Lithuania}} !! {{flagicon|Poland}} !! {{flagicon|Russia}}
|-
| '''{{flag|Belarus}}''' ||align="center"| - || 502 || 407 || 959
|-
| '''{{flag|Lithuania}}''' || 502 ||align="center"| - || 91 || 227
|-
| '''{{flag|Poland}}''' || 407 || 91 ||align="center"| - || 206
|-
| '''{{flag|Russia}}''' || 959 || 227 || 206 ||align="center"| -
|}
===Belarus-Poland-Russia-Ukraine===
This set has existed since the [[1991]] [[History of the Soviet Union (1985–1991)#Dissolution of the USSR|Dissolution of the Soviet Union]].
The Russian [[Kaliningrad Oblast]], an exclave on the [[Baltic Sea]], creates a [[Russia]]n border with [[Poland]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Belarus}} !! {{flagicon|Poland}} !! {{flagicon|Russia}} !! {{flagicon|Ukraine}}
|-
| '''{{flag|Belarus}}''' ||align="center"| - || 407 || 959 || 891
|-
| '''{{flag|Poland}}''' || 407 ||align="center"| - || 227 || 428
|-
| '''{{flag|Russia}}''' || 959 || 227 ||align="center"| - || 1576
|-
| '''{{flag|Ukraine}}''' || 891 || 428 || 1576 ||align="center"| -
|}
==Western Europe==
===Belgium-Germany-Kingdom of the Netherlands-France===
[[Image:BEL-GER-FRA-NED.png|right|thumb|Map of Belgium|'''Germany''' (green) and '''Belgium''' (red), '''France''' (blue) and the '''Kingdom of the Netherlands''' (magenta)]]
This set has existed since the [[1830]] [[Belgian Revolution|Independence of Belgium]]. Even though the German lands have had many territorial changes, [[Prussia]]'s [[Rhine Province]] and later the various unified German states have always bordered the other three countries.
The only land boundary between the Kingdom of the Netherlands and France is on the Caribbean island of [[Saint Martin]] (Sint Maarten), where the [[Netherlands Antilles]] meets the [[Saint Martin (France)|French Overseas Collectivity of Saint Martin]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Belgium}} !! {{flagicon|Germany}} !! {{flagicon|Netherlands}} !! {{flagicon|France}}
|-
| '''{{flag|Belgium}}''' ||align="center"| - || 167 || 450 || 620
|-
| '''{{flag|Germany}}''' || 167 ||align="center"| - || 577 || 451
|-
| '''{{flag|Netherlands}}''' || 450 || 577 ||align="center"| - || 10
|-
| '''{{flag|France}}''' || 620 || 451 || 10 ||align="center"| -
|}
===Luxembourg-France-Germany-Belgium===
[[Image:LUX-FRA-GER-BEL.png|right|thumb|Map of Luxembourg|'''Luxembourg''' (red), '''France''' (blue), '''Germany''' (green), and '''Belgium''' (magenta)]]
This set has existed since the [[1839]] [[Treaty of London (1839)|independence of Luxembourg]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Luxembourg}} !! {{flagicon|France}} !! {{flagicon|Germany}} !! {{flagicon|Belgium}}
|-
| '''{{flag|Luxembourg}}''' ||align="center"| - || 73 || 138 || 148
|-
| '''{{flag|France}}''' || 73 ||align="center"| - || 451 || 620
|-
| '''{{flag|Germany}}''' || 138 || 451 ||align="center"| - || 167
|-
| '''{{flag|Belgium}}''' || 148 || 620 || 167 ||align="center"| -
|}
==Balkans==
===Bosnia and Herzegovina-Serbia-Montenegro-Croatia===
[[Image:BIH-SRB-MNE-CRO.png|right|thumb|Map of Bosnia and Herzegovina|'''Bosnia and Herzegovina''' (red), '''Serbia''' (blue), '''Montenegro''' (green), and '''Croatia''' (magenta)]]
This set has existed since the [[2006]] [[Montenegrin independence referendum, 2006|independence of Montenegro]].
[[Bosnia and Herzegovina]] has 20 km of coastline on the Adriatic Sea while Croatia borders Montenegro only through the non-contiguous southern portion of the Dubrovačko-neretvanska county, which is technically an exclave, though is connected to the rest of Croatia by territorial waters.
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Bosnia and Herzegovina}} !! {{flagicon|Serbia}} !! {{flagicon|Montenegro}} !! {{flagicon|Croatia}}
|-
| '''{{flag|Bosnia and Herzegovina}}''' ||align="center"| - || 302 || 225 || 932
|-
| '''{{flag|Serbia}}''' || 302 ||align="center"| - || 203 || 241
|-
| '''{{flag|Montenegro}}''' || 225 || 203 ||align="center"| - || 25
|-
| '''{{flag|Croatia}}''' || 932 || 241 || 25 ||align="center"| -
|}
==Caucasus==
===Azerbaijan-Armenia-Turkey-Iran===
[[Image:AZE-ARM-TUR-IRN.png|right|thumb|Map of Nakhichevan Region of Azerbaijan|'''Azerbaijan''' (red), '''Armenia''' (green), '''Turkey''' (magenta), and '''Iran''' (blue)]]
This set has existed since the [[1991]] [[History of the Soviet Union (1985–1991)#Dissolution of the USSR|Dissolution of the Soviet Union]]. Azerbaijan has a border with Turkey through its exclave of [[Nakhichevan]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Azerbaijan}} !! {{flagicon|Armenia}} !! {{flagicon|Turkey}} !! {{flagicon|Iran}}
|-
|'''{{flag|Azerbaijan}}''' ||align="center"| - || 787 || 9 || 611
|-
|'''{{flag|Armenia}}''' || 787 ||align="center"| - || 268 || 35
|-
|'''{{flag|Turkey}}''' || 9 || 268 ||align="center"| - || 499
|-
|'''{{flag|Iran}}''' || 611 || 35 || 499 ||align="center"| -
|}
===Azerbaijan-Armenia-Georgia-Turkey===
This set has existed since the [[1991]] [[History of the Soviet Union (1985–1991)#Dissolution of the USSR|Dissolution of the Soviet Union]]. Azerbaijan has a border with Turkey through its exclave of [[Nakhichevan]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Azerbaijan}} !! {{flagicon|Armenia}} !! {{flagicon|Georgia}} !! {{flagicon|Turkey}}
|-
|'''{{flag|Azerbaijan}}''' ||align="center"| - || 787 || 322 || 9
|-
|'''{{flag|Armenia}}''' || 787 ||align="center"| - || 164 || 268
|-
|'''{{flag|Georgia}}''' || 322 || 164 ||align="center"| - || 252
|-
|'''{{flag|Turkey}}''' || 9 || 268 || 252 ||align="center"| -
|}
==Africa==
===Burundi-Rwanda-Tanzania-Democratic Republic of the Congo===
[[Image:BDI-RWA-TAN-COD.png|right|thumb|Map of Burundi|'''Burundi''' (green), '''Rwanda''' (red), '''Tanzania''' (blue), and '''DR Congo''' (magenta)]]
This set has existed since the [[1962]] change of the united Belgian colony of [[Ruanda-Urundi]] into the independent states of [[Burundi]] and [[Rwanda]]. [[Democratic Republic of the Congo|Congo]] had achieved independence in 1960 and was followed the next year by Tanganyika, which would later merge with Zanzibar to form [[Tanzania]]. The border between DR Congo and Tanzania is entirely aquatic; the two nations are separated by [[Lake Tanganyika]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Burundi}} !! {{flagicon|Rwanda}} !! {{flagicon|Tanzania}} !!{{flagicon|Democratic_Republic_of_the_Congo}}
|-
| '''{{flag|Burundi}}''' ||align="center"| - || 209 || 451 || 233
|-
| '''{{flag|Rwanda}}''' || 209 ||align="center"| - || 217 || 217
|-
| '''{{flag|Tanzania}}''' || 451 || 217 ||align="center"| - || 459
|-
| '''{{flag|Democratic Republic of the Congo}}''' || 233 || 217 || 459 ||align="center"| -
|}
===Rwanda-Uganda-Democratic Republic of the Congo-Tanzania===
[[Image:RWA-UGA-COD-TAN.png|right|thumb|Map of Rwanda|'''Rwanda''' (red), '''Uganda''' (green), '''DR Congo''' (magenta), and '''Tanzania''' (blue)]]
By the time of [[Uganda]]n independence in [[1962]], all of the borders of this set were already established. DR Congo and Tanzania are separated by [[Lake Tanganyika]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Rwanda}} !! {{flagicon|Uganda}} !! {{flagicon|Democratic_Republic_of_the_Congo}} !! {{flagicon|Tanzania}}
|-
| '''{{flag|Rwanda}}''' ||align="center"| - || 169 || 217 || 217
|-
| '''{{flag|Uganda}}''' || 169 ||align="center"| - || 765 || 396
|-
| '''{{flag|Democratic Republic of the Congo}}''' || 217 || 765 ||align="center"| - || 459
|-
| '''{{flag|Tanzania}}''' || 217 || 396 || 459 ||align="center"| -
|}
===Malawi-Mozambique-Zambia-Tanzania===
[[Image:MWI-MOZ-ZAM-TAN.png|right|thumb|Map of Malawi|'''Malawi''' (red), '''Mozambique''' (magenta), '''Zambia''' (green), and '''Tanzania''' (blue)]]
This set has existed since the [[1964]] independence of [[Zambia]] and [[Malawi]]. [[Mozambique]] became independent from Portugal in [[1975]].
{| class="wikitable" style="text-align:center"; border="50"
! Borders (km) !! {{flagicon|Malawi}} !! {{flagicon|Mozambique}} !! {{flagicon|Zambia}} !! {{flagicon|Tanzania}}
|-
| '''{{flag|Malawi}}''' ||align="center"| - || 1569 || 837 || 475
|-
| '''{{flag|Mozambique}}''' || 1569 ||align="center"| - || 419 || 756
|-
| '''{{flag|Zambia}}''' || 837 || 419 ||align="center"| - || 338
|-
| '''{{flag|Tanzania}}''' || 475 || 756 || 338 ||align="center"| -
|}
==Near misses==
*The 40 km border between China's [[Xinjiang]] Autonomous Region and Russia's [[Altai Republic]] prevents [[Mongolia]], [[Kazakhstan]], [[Russia]], and the [[People's Republic of China]] from forming a set of four countries that border one another.
*The short border between [[Sikkim]] in [[India]] and [[Tibet]] in the [[People's Republic of China]] prevents the group [[Bhutan]], [[India]], [[Nepal]] and the [[People's Republic of China]] from forming such a set.
*The 2 km border between Zambia and Botswana at Africa's "four corners" is all that prevents the group [[Botswana]]-[[Namibia]]-[[Zimbabwe]]-[[Zambia]] from satisfying the criteria of four nations that border one another (see [[Quadripoint#International quadripoints|International quadripoints]] for more information).
==Former border sets of at least four countries==
The first two sets below include boundaries shared by former colonial empires (specifically territorial claims in [[South_america#European_colonization|South America]], [[Colonial Africa|Africa]], [[Colonial India|India]], [[History of Europe|Europe]], and the [[East India Company|East]] and [[West India Company|West]] Indies), and thus do not reflect continuous areas of land.
{| class="wikitable" style="text-align:center"; border="50"
! Countries !! From !! To !! Terminal Event
|-
| {{flag|France|early}} <ref>Between 1704 and 1713, [[French colonial empire|France]] and her colonies neighbored the Netherlands (on [[Saint Martin]]), Spain (in Europe), Portugal (between [[French Guyana]] and Portuguese [[Brazil]]) and Great Britain (between the [[Colonial India|Indian]] settlements of [[Hugli-Chuchura#History|Hughli]] and [[Chandernagar]]).</ref>, {{flag|Dutch Republic}} <ref>Between 1704 and 1713, the [[Dutch Empire|Netherlands]] and her colonies neighbored France (on [[Saint Martin]]), Spain (in Europe between [[Dutch Republic]] and the [[Spanish Netherlands]]), Portugal (between Dutch [[Suriname]] and Portuguese [[Brazil]]), and Great Britain (between the [[Colonial India|Indian]] settlements of [[Pulicat]] and [[Madras]].</ref>, {{flag|Spain|1701}} <ref>Between 1704 and 1713, [[Spanish Empire|Spain]] and her colonies neighbored France (in Europe), the Netherlands (in Europe between [[Spanish Netherlands]] and the [[Dutch Republic]]), Portugal (in Europe and South America), and Great Britain (with the 1704 British capture of [[Gibraltar]]).</ref>, {{flag|Portugal|1707}} <ref>Between 1704 and 1713, [[Portuguese Empire|Portugal]] and her colonies neighbored France (between Portuguese [[Brazil]] and [[French Guyana]]), the Netherlands (between Brazil and Dutch [[Suriname]]), Spain (in Europe and South America), and Great Britain (between the [[Colonial India|Indian]] settlements of [[Daman and Diu]] and [[Surat]]).</ref>, {{flag|United Kingdom|1606}} <ref>Between 1704 and 1713, the [[Kingdom of Great Britain]] (and prior to the 1707 [[Acts of Union 1707|Acts of Union]], the [[Kingdom of England]]) and her colonies neighbored France (between the [[Colonial India|Indian]] settlements of [[Chandernagar]] and [[Hugli-Chuchura#History|Hughli]]), the Netherlands (between the [[Colonial India|Indian]] settlements of [[Madras]] and [[Pulicat]]), Spain (with the 1704 British capture of [[Gibraltar]]), and Portugal (between the [[Colonial India|Indian]] settlements of [[Daman and Diu]] and [[Surat]])</ref> || 1704 || 1713 || Signing of the [[Treaty of Utrecht]] on [[11 April]] [[1713]]
|-
| {{flag|Belgium}}<ref>European [[Belgium]] bordered France, the Netherlands, and Germany. The [[Belgian Congo]] bordered Portuguese Angola and several French and British colonies in Africa.</ref>, {{flag|Portugal}}<ref>European [[Portugal]] bordered Spain. In 1914, the African colonies of Mozambique, Angola, and Guinea-Bissau bordered territories held by Germany (Namibia and Tanganyika), Great Britain, France, and Belgium. The colony of [[East Timor|Timor Leste]] bordered the Dutch East Indies.</ref>, {{flag|German Empire}}<ref>Immediately prior to [[World War I]], European [[German Empire|Germany]] bordered the Netherlands, Belgium, and France. African colonies shared boundaries with territories held by Great Britain, Portugal, France, and Belgium</ref>, {{flag|France}}<ref>European [[France]] shared borders with Belgium and Germany. Vast French holdings in [[Scramble for Africa|colonial Africa]] abutted colonies possessed by Great Britain, Belgium, Germany, and Portugal. In South America, [[French Guyana]] bordered Dutch Suriname.</ref>, {{flag|United Kingdom}}<ref>British colonies in Africa shared boundaries with territories held by France, Belgium, Germany, and Portugal. In South America, [[History of Guyana|British Guyana]] bordered Dutch Suriname.</ref>, {{flag|Netherlands}}<ref>The European [[Netherlands]] shared borders with Germany and Belgium. The Dutch [[Dutch East India Company|East]]and [[Dutch West India Company|West]] India Companies controlled territories that bordered colonies of Portugal (on the island of Timor), Great Britain (Guyana), and France (French Guyana).</ref> || late 1800s || 1914 || Outbreak of [[World War I]]
|-
| {{flag|France}}, {{Flag|Germany|[...]}}, {{flag|Italy|1861}}, {{flag|Switzerland}} || 1938 || 1945 || The dissolution of Germany into allied occupation zones<ref>Date of dissolution assumes that France continued to exist, and include the Occupied Zones, after June 1940; this phrasing ignores the ''de facto'' existence of the [[Italian Social Republic]] from 1943 on, which was adjacent to the other three states until its last days. The exact date at which a new Austria came into existence may be debatable.</ref>
|-
| {{flag|Burma}}, {{flag|China}}, {{flag|India}}, {{flag|Pakistan}}<ref>From 15 August 1947 to 16 December 1971, Pakistan included modern-day Bangladesh (known as [[East Pakistan]])</ref> || 1947 || 1971 || Independence of [[Bangladesh]]
|-
| {{flag|Kosovo}} (under UN administration)<ref>The United Nations has been administering the region of Kosovo (in southern Serbia) since 1999</ref>, {{flag|Serbia and Montenegro|name=Federal Republic of Yugoslavia}}<ref>On 4 February 2003, the Federal Republic of Yugoslavia was renamed to [[Serbia and Montenegro]]</ref>, {{flag|Albania}}, {{flag|Macedonia}} || 1999 || 2006 || Formal dissolution of the [[Serbia and Montenegro|State Union of Serbia and Montenegro]]
|}
==See also==
* [[Four colour theorem]]
* [[List of land border lengths]]
* [[List of political and geographic borders]]
* [[List of countries that border only one other country]]
* [[List of national border changes since World War I]]
* [[List of island nations]]
* [[List of divided islands]]
* [[Landlocked]]
* [[Enclave]]
* [[List of enclaves and exclaves]]
* [[Foreign Enclaves in China]]
* [[Island country]]
* [[Quadripoint]]
==Notes==
<div class="references-small" style="-moz-column-count:2; column-count:2;">
<references /></div>
== Sources ==
*CIA World Factbook [https://www.cia.gov/library/publications// CIA World Factbook] (public domain)
[[Category:Lists of countries|Borders, land]]
[[Category:Borders]]