Complex sentence: As the Eastern Han Dynasty slowly disintegrated into an era of "warlords", battles for predominance eventually ushered in the Three Kingdoms; however years of war generated a severe shortage of labor, a solution to which was encouragement of immigration of Wu Hu herdsmen.
Split into simpler sentences: As the Eastern Han Dynasty slowly disintegrated into an era of "warlords", battles for predominance eventually ushered in the Three Kingdoms. However years of war had generated a severe shortage of labor, a solution to which was the encouragement of immigration of Wu Hu herdsmen.