Buddhism begins to spread
Mahayana or the larger vehicle or wheel is not just for the Sangha. Rather it helps everyone along the path towards enlightenment. Just because it is called the larger, does not mean it is more important than the Theravada. Both are equally important, and neither could exist without the other. This is the main form found in China, Korea, Japan and northern Asia. Vietnam has a unique blend of Theravada and Mahayana blended, as befits that Buddhism came from the Indian sub-continent as well as from China to the north. Tibetan Buddhism calls itself Vajrayana(Indestructible Path) which is a union of Theravada and Mahayana. Regardless of which path of school, they all are based on the same teachings, and all lead to enlightenment. Also with the shifting of empires over the centuries since Buddha, from King Ashoka in the 200s B.C.E. who helped spread Buddhism as far as Syria, Egypt and Macedonia., to the Mongols who changed sociological viewpoints in SE Asia, resulting in the loss of Buddhist nuns in the area. Buddhism has adapted and blended in each region. Just as tofu is a nutritious food that takes on the flavours of the food it is cooked with, so has Buddhism adopted to each era and country.