Complex sentence: In 1596 Sir Walter Raleigh mentioned the arrow poison in his book "Discovery of the Large, Rich, and Beautiful Empire of Guiana" (now Guyana), though it is possible that the poison he described was not curare at all.
Split into simpler sentences: In 1596 Sir Walter Raleigh mentioned the arrow poison in his book "Discovery of the Large, Rich, and Beautiful Empire of Guiana" (now Guyana). It is possible that the poison he described was not curare at all.