Geographic tiling
Also: quadtree tiling, map tiling
Splitting a map area into smaller rectangles and querying each one separately, so that a per-query result cap stops limiting how much of the area you can see.
It is the standard answer to a search API that returns a bounded set regardless of how you ask. The recursive form splits only the tiles that came back full, which keeps the request count proportional to how dense an area actually is rather than to how large it is.