Enclaves appear when history contrives to put a piece of one country completely inside another. India and Bangladesh's border is a maze of them, but they've just fixed the craziest of them all: an enclave surrounded by an enclave surrounded by an enclave surrounded by another state.
Attempts to rectify the situation have stalled for decades: An agreement for a land swap was reached in 1974, but India did not ratify it. In 2011, however, a new agreement was reached, which, after some stalling, was finally ratified in June. The enclaves will become territory of the states that surround them and the citizens who live within them will get to decide whether they want to stay put and accept new citizenship, or whether they want to keep their original citizenship and be relocated.