nothing was stolen. poland abolished their own sovereignty and formed the plc. also, technically, germany via prussia as the sole state which can trace its roots back to medieval poland has a claim on the former polish kindom. the polish kingdom is not the plc.  the plc was formed from two-states and was ruled by balts. the plc was then destroyed in a series of wars. prussia, and therefore germany, is the only actual successor of the kingdom of poland from the middle ages.
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