Complex sentence: Under Tudhaliya I-II, Sapinuwa was burnt, and Samuha became the base for the reconquests of Tudhaliya III and his then-general Suppiluliuma.
Split into simpler sentences: Under Tudhaliya I-II, Sapinuwa was burnt. Samuha then became the base for the reconquests of Tudhaliya III and his then-general Suppiluliuma.