Biryani came to India with Mughal (Persian) influence — the word shares roots with biryan, "fried/roasted" in Persian. The core idea: rice + meat + spices, layered and slow-cooked together. But every region took this and made it its own. Two fundamental methods:
kachchi — raw marinated meat is layered under rice and cooked together; the meat steams in its own juices. Riskier, more flavorful. Hyderabadi is the classic.
pakki — meat is cooked separately first, then layered with pre-cooked rice. Safer, more consistent. Lucknawi is classic.