Complex sentence: Dubnow's political thought can better be understood in light of historical Jewish communal life in Eastern Europe, especially as it reached full development during the early period of the Polish-Lithuanian Commonwealth (1569-1795).
Split into simpler sentences: Dubnow's political thought perhaps can better be understood in light of historical Jewish communal life in Eastern Europe. It florished during the early period of the Polish-Lithuanian Commonwealth (1569-1795).