strong alliances

[V.T. Marvin]

One crucial thing, IMO, is to keep your ally occupied by a war with somebody else.

In my Roman campaign, I have owned Emporion and Arse, the rest of Iberian penninsula was taken by the Lusitani (my allies) except Gader, which was still owned by the Carthaginians (common enemy of mine and the Lusotanna). I purposefully evaded attacking Gader just to keep the Luso occupied. And yes, they kept their alliance for more than 50 years (200 turns!!!) of our common border until they finally conquered Gader. The next turn, they betrayed me...

In the same campaign Arverni are still loyal allies of mine for more than 100 years (400 turns) of long shared border, because they are still unable to subdue the Aedui (who are reduced to one city, but putting up a heroic resistance).

The same situation is in Dalmatia, where I own Dalminion and Segestica without war with either Getai (allies) or Epeiros (neutral) for almost 100 years as the two are locked in mutual struggle among themselves...

[DaciaJC]

One crucial thing, IMO, is to keep your ally occupied by a war with somebody else.

In my Roman campaign, I have owned Emporion and Arse, the rest of Iberian penninsula was taken by the Lusitani (my allies) except Gader, which was still owned by the Carthaginians (common enemy of mine and the Lusotanna). I purposefully evaded attacking Gader just to keep the Luso occupied. And yes, they kept their alliance for more than 50 years (200 turns!!!) of our common border until they finally conquered Gader. The next turn, they betrayed me...

You exactly described my Romani campaign there.