The culture in Southeast Asia is very diverse: on mainland Southeast Asia, the culture is a mix of Indochinese (Burma, Cambodia, Laos and Thailand) and Chinese (Singapore and Vietnam). While in Indonesia, the Philippines and Malaysia the culture is a mix of indigenous Austronesian, Indian, Islamic, Western, and Chinese cultures. Also Brunei shows a strong influence from Arabia. Singapore and Vietnam show more Chinese influence in that Singapore, although being geographically a Southeast Asian nation, is home to a large Chinese majority and Vietnam was in China's sphere of influence for much of its history. Indian influence in Singapore is only evident through the Tamil migrants, which influenced, to some extent, the cuisine of Singapore. Throughout Vietnam's history, it has had no direct influence from India - only through contact with the Thai, Khmer and Cham peoples.
Where in Southeast Asia is the culture not very divers? (If the question is unanswerable, say "unanswerable")
unanswerable