Complex sentence: In 1922, Yasue and Inuzuka had returned from the Japanese Siberian Intervention, aiding the White Russians against the Red Army where they first learned of the "Protocols" and came to be fascinated by the alleged powers of the Jewish people.
Split into simpler sentences: In 1922, Yasue and Inuzuka returned from the Japanese Siberian Intervention, aiding the White Russians against the Red Army. This is where they first learned of the "Protocols" and came to be fascinated by the alleged powers of the Jewish people.