Northwest India was a historical region, geographically located on the north-western Indian subcontinent. It predominantly constitutes what are now parts of the present-day South Asian republics of India and Pakistan (specifically modern north-western India and eastern Pakistan) after the 1947 Partition of British India. Until the Iron Age, the term "India" predominantly referred to this region (the Indus valley). The region encompassed the modern Pakistan and the territory of the modern India approximately to the west of the 77th meridian east and north of the 24th parallel north. History The Indus Valley Civilisation formed in the northwestern subcontinent over 4000 years ago, with climate change potentially having caused its later decline. Northwest India was a hub of Buddhism in ancient times, and was the region from which Buddhism reached China by travelling through Central Asia. The Umayyad Caliphate conquered Sindh in the 8th century CE, marking the beginning of what was to become a major Islamic presence in the region.