How does an invasionary force conquer a foreign land where they are outnumbered other than by being warlike? Lets define warlike as those who have achieved a h

How does an invasionary force conquer a foreign land where they are outnumbered other than by being warlike? Lets define warlike as those who have achieved a high degree of skill at warfare. The Mongols who conquered cities and states were famously warlike. So were the Macedonians/Greeks under Alexander.