Traditions travel, and regions are meeting-points as much as origins. Ideas, gods and techniques moved along trade and conquest routes (Babylonian astronomy into Greece, Greek philosophy into the Islamic world and back into Europe, Buddhism across Asia), and a region's religious life is usually a layered product of exchange rather than a sealed local growth.
The entries note these movements where they matter, so a region reads not as an isolated box but as a node in a larger web of contact, from which the more specific categories here (deities, sites, texts), can be entered.