I watched to the "end" but it was cancelled before it actually finished

Vikings wasn't cancelled before it finished -- History Channel announced that the 6th season would be the last, and it ended when and how the showrunner, Michael Hirst, had always envisioned it would -- with the Vikings arriving in North America. It was Hirst's decision to split season 6 into two parts, and when and how to end it.

There's also the sequel now on Netflix -- Vikings: Valhalla.