If your team's event is going to be in your colleagues' geographic territory, tell them about it.
Even if it doesn't directly involve them?
Tell them anyway. Think of it as a courtesy. Besides that, something more substantive may surface. A related point: If the action falls in a hazy area between your turf and theirs, consult them in advance.
Isn't that going to take time?
Sure, but it will save time down the road by preventing misunderstandings and hurt feelings. Go with this simple rule: If in doubt, coordinate. It fosters trust and trust is the coin of the realm.