Is this strategy viable?

[das123]

I was playing a game the other day but for a number of reasons couldn't start expanding until fairly late. It was hard work but I slowly fought off the hordes attacking my core provinces and eventually had a good quality army that ultimately wiped out one of the antagonists (before a water nation wiped me out).

Usually I expand and protect as quickly as I can but the side benefit of being attacked so close to home was that when I finally re-took the provinces, the enemy hordes had discovered caches of special sites.

Is this holding back and getting attacked a viable strategy or is it still best to get as many provinces as possible in the early game?