system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Southeast Asians have lighter-skin colors compared to other peoples at the same latitude?

For background, I'm of southern Chinese background. I'm pretty light/fair-skinned (although I am the youngest in my family - because I'm 12 years old, so my skin color will probably get darker as I get older). 

Almost all Southeast Asians (Thais, Vietnamese, Cantonese, etc.) have lighter skin color than Indians or Africans even though they are located at the same latitude as Indians and Africans.

Since Southeast Asia is tropical and sunny, why aren't they as dark skinned as Indians or Africans?
gpt
China has had a huge influence in that region for most its history. The Thai-Kadai peoples (Laos and Thailand) are native to south China around Guangxi (where the Zhuang still are) and migrated to southeast Asia during the time China was expanding (~1200 years ago) which displaced Austroasiatic peoples like the Khmer (Cambodians) and Vietnamese (which was ruled by China several times). Burmese are Sino-Tibetans (same group as the Chinese) and are also descendants of earlier migrations. You never had largescale migrations of peoples from India to southeast Asia but instead just religion and customs. 

Your Austronesians like the Malay and the other many languages of Indonesia and the Philippines originate from peoples who migrated from south China to Taiwan (around 8 thousand years ago) who then migrated south. They displaced the native Negritos who are dark skinned.