IcantHear, I am afraid that you are just expanding too slowly. I have posted three playthroughs over the last few months. The were all on large maps, at Ridiculous and Insane difficulties and by turn 50-60 I had scouted all the AIs.
In the first two, by turns 100, all the opposite alignment AIs were dead. In the third, I was deliberately not starting any wars, and only expanding by colonization and influence push. By turn 65, the population/city count, according to the "foreign relation" screen were:
My side 664 (9 cities)
Gilden 916 (6)
Tarth 828 (8)
Kraxis 300 (3)
Altar 566 (2)
Magnar 604 (7)
Yithril 507 (5)
Resoln 150 (1)
As you can see, some AIs spread much faster. In that case, it was because some started in cramped positions, near other players, while others (Tarth, Gilden and Magnar) had started pretty much in a column in the middle of the map, with no one on their West.
You said that you had a nasty surprise by turn "couple of hundreds". Well, you can be way beyond surprises by that time. So just stick with the game, and work on early scouting and land grab.
If you want to look at the playthroughs, they can be found here, here and here. Word of caution. They are each from different releases, and many strategies will no longer work. The one that will still work (better than ever) in .96 is "Self buffing heroes conquering the world"