Complex sentence: Scholars such as Ruan saw astronomy and mathematics as a key to deciphering the ancient classics, and until the Sino-Japanese War many believed that the science and technology coming from Europe was actually lost ancient Chinese knowledge.
Split into simpler sentences: Scholars such as Ruan saw astronomy and mathematics as a key to deciphering the ancient classics. Until the Sino-Japanese War, many believed that the science and technology coming from Europe was actually lost ancient Chinese knowledge.