Guys I have a Wings of Fire theory. (Sorry in advance, it's 4 am and I can't sleep)
As we know, Nightwings, Icewings, Sandwings, and Seawings have animus dragons and Skywings, Rainwings and Mudwings do not. However, we know that Skywings USED to have animus dragons before they killed them all off.
The Nightwings and Seawings both got their animus magic from Icewings. However, how did the Sandwings get their animus powers? And skywings for that matter?
What if other tribes (like Rainwings and Mudwings) USED to have animus dragons too and just killed them all off like the Skywings later did?