Complex sentence: Unfortunately, most of his works were ruined or destroyed in the turmoil of the Sengoku period, however those that do still exist provide testimony to his talent, power and wealth of his patrons Nobunaga and Hideyoshi, and magnificence of Azuchi-Momoyama culture.
Split into simpler sentences: Unfortunately, most of his works were ruined or destroyed in the turmoil of the Sengoku period. However, those that do still exist provide testimony to his talent, to the power and wealth of his patrons Nobunaga and Hideyoshi, and to the magnificence of Azuchi-Momoyama culture.