Complex sentence: By the 1930s, their value had decreased; in 1937, A. J. Arkell recorded the beads being sold "for a song" by Sudanese women to Hausa traders in Dafur.
Split into simpler sentences: By the 1930s, their value had decreased. In 1937, A. J. Arkell recorded them being sold "for a song" by Sudanese women to Hausa traders in Dafur.