Voltron did come before Transformers. In Japan it was called Beast King GoLion. It premiered march 4th 1981. The animation from GoLion was edited and trimmed to create the Lion version of the U.S. Voltron: Defender of the Universe series, with new names and dialogue, as well as several plot changes. Then came vehicle Voltron. which was based on Kikou Kantai Dairugger XV. It premeired March 3, 1982. Dairugger and GoLion had no connection in Japan. Another unrelated series (Lightspeed ElectroGod Albegas, March 30, 1983) was going to be the third Voltron series, but fans didn't like vehicle enough for it to make sense to do the third series. All 3 series were before Transformers.
If anyone wants to learn Monsterpocalypes I have plenty of extra figs and am usually around on weekends