"Adat" derives in part from the ancient animist and buddhist belief system of the Minangkabau, which existed before the arrival of Islam to Sumatra. When precisely the religion spread across the island and was adopted by the Minangkabau is unclear, though it probably arrived in West Sumatra around the 16th century. It is "adat" that guides matrilineal inheritance, and though it seems that such a tradition might conflict with the precepts of Islam, the Minangnese insist that it does not. To accommodate both, the Minangkabau make a distinction between high and low inheritance. “High inheritance” is the property, including the home and land, which passes among women. “Low inheritance” is what a father passes to his children out of his professional earnings. This latter inheritance follows Islamic law, a complex system which dictates, in part, that sons get twice as much as daughters.