West Malaysia is the Malay Peninsula, not the Thai, Indian/Chinese peninsula. -Srivijayan Malays may have been victorious in Sumatra, but Malays still come from the Malay Peninsula and ancient Indochina, who were marginalized by new arrivals from South China, namely the ancestors of the Vietnamese, Thais and others who made Indochina what it is today. -There is no history of the origin of the nation emerging from an island. -Japan alone claims that its ancestors came from the Korean peninsula who migrated to the island of Japan. -Conclusion:Malaysian Malays are not immigrants from Sumatra. -The Sumatran Malays are also not immigrants, they are natives of the island of Sumatra, just like the Japanese on the island of Japan.