Climbing over 7000m peaks is the best way to prepare for the 8000m, Nepal has popular 7000m peaks like Himlung, Baruntse, Tilicho, and Amadablam (6812m, which is also considered a 7k peak)
The 8 highest peaks over 8000 meters out of 14 in the world are only located in Nepal, making it the top destination for mountaineers around the world.