It doesn't help that there's also cultural differences. I've been in a similar turf war between an Israeli team and myself as an ex-Israeli on a different team

It doesn't help that there's also cultural differences. I've been in a similar turf war between an Israeli team and myself as an ex-Israeli on a different team and there was just a huge gap in how things are done. Both teams could have probably delivered just fine but top management is what really messed things up. So really this is probably mostly lack of leadership, and the turf wars are more of a symptom... The lack of leadership is often not just in being unable to resolve/deal/manage a larger org. but also the hiring of more managers who are unable to do this stuff that eventually get promoted to positions where they end up doing more harm. I'm not sure the engineers themselves having a big ego is a negative. I'd want a team who thinks they can do anything. But how you manage those guys is the problem...