Complex sentence: Part of NSZ joined the Armia Krajowa in March 1944, where after the faction that did not join was known as NSZ-ZJ (after "Zwiazek Jaszczurczy" or the "Salamander Union").
Split into simpler sentences: Part of NSZ joined the Armia Krajowa in March of 1944. The one arm that did not join was known as NSZ-ZJ (after "Związek Jaszczurczy" or the "Salamander Union").