Pride I suspect is a large difference. While it might be accepted to alliance of neighbors foreign "others" don't cut it unless conquered as it doesn't vicariou

Pride I suspect is a large difference. While it might be accepted to alliance of neighbors foreign "others" don't cut it unless conquered as it doesn't vicariously massage their ego the same way to have partners with agency. It seems to go back to before nationalism per se as a term. See Genhis Khan and the Mongols who ironically had little cultural influence over those they once conquered. Just uniting into a lack of war wasn't enough - they needed outside targets. Feudalism in general had that issue where a post unified country is left with an excess of fighters to burn off on foreign adventures for stability to prevent infighting fiefdom expansions. Both Japan post Sengoku Jidai and the Crusades fit that model as well. It also made them long term enemies even jf it didn't result in same generation "show up to pillage your holdings" retaliation.