Steppe by Steppe

Needs Khans of the Steppe: start as an eastern-steppe nomad and migrate your horde all the way west. The wiki's practical notes: you can SHRINK your horde for the migration target - dropping to a county-level horde for the final hop avoids fighting confederations (whose coalition stacks can hit five or six digits), and there's usually at least one independent or herder-held county in the west to slot into. Watch the books after shrinking - too many men-at-arms on a county-sized income goes negative fast, but keep enough army to survive the trip. Go west, young khan.