Southeast Asia or Southeastern Asia, is the southeastern part of Asia. There are ten countries in this region. All the countries in Southeast Asia are a part of ASEAN, except for East Timor. Some of the countries are mostly on the Asian mainland; they were formerly called Indochina. The others are only on islands. All of the countries in Southeast Asia are in the tropics except for the northernmost areas of Myanmar, which is in the subtropics. These are the countries in Southeast Asia: