Traditional accounts of the ancestral roots of Mangalorean Catholics have taught that they are descended from the Indo-Aryans who lived on the banks of the now extinct Saraswati River. That is the Goud Saraswath Brahmins. Most historians agree that the Aryans descended into India from the areas of present-day Iran, and some came by themselves, while others came with their leaders in search of territorial expansions. The Saraswati river dried up in long stretches around 1500 BCE, when its source in the Himalayas got diverted into the Yamuna River due to sand deposition and river piracy. Due to the harshness in their native environments, several Indo-Aryan groups migrated to various different locations across India. According to Historian Alan Machado Prabhu, the modern Mangalorean Catholic community is mainly descended from two Indo-Aryan groups: the group which migrated to the Konkan coast and Goa; and the group which migrated to Bengal.