In the reservation system, American Indian tribes were confined to assigned land with defined borders
flexible borders
unknown borders
natural borders

china has confucianism thats everywhere in asia but it isn't really a religion.  

one central belief of buddhism is often referred to as reincarnation -- the concept that people are reborn after dying. buddhism is a philosophy of life expounded by gautama buddha ("buddha" means "enlightened one"), who lived and taught in northern india in the 6th century b.c.

i see, would you mind putting it as one?

geography

this is because warmer climates often don't get people sick from the flu and regions where it was often colder more people received the flu. hope this if you need more reasoning i am here to