Complex sentence: At the time, Lisa was legally married to a European-American woman in St. Louis, where she lived full-time; after her death in 1817, he married a second woman of European descent in St. Louis.
Split into simpler sentences: At the time, Lisa was legally married to a European-American woman in St. Louis, where she lived full-time. After her death in 1817, he married a second woman of European descent in St. Louis.