Final answer:
The physical environment of Southeast Asia is characterized by its tropical climate, complex maritime boundaries, and numerous islands. The region is also ethnically diverse, with multiple ethnic groups and overseas Chinese immigrants.
Step-by-step explanation:
The physical environment of Southeast Asia is unusual due to several factors. Firstly, the region is located in the tropics, except for the northernmost region of Myanmar. This means that a tropical climate dominates the area, with abundant rainfall. The region is also surrounded by various seas, bays, straits, and gulfs that create complex maritime boundaries. The South China Sea, in particular, acts as a separator between the mainland and the insular region. Additionally, Southeast Asia is characterized by its thousands of islands, which create a unique physical geography.
Moreover, Southeast Asia has a diverse ethnic, religious, and linguistic makeup. While there are major ethnic groups dominating the region, there are also numerous smaller groups. One minority group in the region is the overseas Chinese who immigrated during the colonial era.