Team: Leapfrog
The Strategy
Rather than each player expanding his own territory from his capital out, two or more players can quickly gain more strategic positions by building as a single territory, each placing his cities ahead of the expansion of the other. There are two principal uses for this technique. First is to territory grab in the centre, when many maps have the best resources. The other use is to apply a far more effective and quicker border push on a flank enemy. This technique is also useful where a known weaker player is located in a vulnerable position on the flank. A stronger player can effectively swap places with them.
A possible down side of this is that it can allow an enemy border push to penetrate deep into your territory where there are gaps. This can be prevented by temple building in all cities and augment vulnerable spots with a castle. Pushing into dominant positions to grab the best resources will only benefit you in the long term but it places your expansion far nearer the enemy lines of supply so military presence and wise placement of facilities needs consideration.
Using this to gain forward bases has the big advantage of taking the fight to the enemy boundaries earlier and gives you shorter paths and more flexible bases to raid and attack from.
The Roles
Any player, flank or pocket can perform leapfrogging, but the purpose of the push needs to be communicated. A push down the flank will lead to a far more imminent military conflict.
The Scenario
Land maps where there are large expanses to capture. Maps with central resources like Southwest Mesa (timber), Great Sahara (metal) and African Watering Hole (rare resources and fishing) benefit most from central expansion.
The Bottom Line
This is more or a technique than a gaming strategy, but it allows a team to take a strategically advantageous position on the map.
Risk: Low
Effectiveness: High