Each Travian server ends with the "end game" sequence. For normal servers the sequence begins after about 280 days, and for Speed3x servers,it starts after about 80 days. After this time has elapsed the Natars, a vicious tribe controlled by the computer, are released. As the players on the server begin to build the Wonder of the World, the plans of which they have captured from the Natars, they meet resistance from both enemy players and alliances and the Natars. With every five levels that the Wonder is upgraded, the Natars attack the villages containing the Wonders until level 95, when they will then attack upon the completion of every new level. The first player to build their World Wonder to level 100 wins the server, which stops and restarts after a period of time (generally about 3 weeks). Then a new game begins, and the cycle repeats.
On T4 the natars and the WW villages are released from the beginning, with something called the grey zone!
And settling in this area will make the natars "angry" at you and they will attack you and try to crush your village using siege weapons and enormous armies. If after many waves of attacks your village still has a certain amount of population, you get to keep the village, but if it is below that number, it gets conquered.
The building plans are still, though, released as normal.
100 days / server speed = artifacts will be set up
200 days / server speed = construction plans will be set up
250 days / server speed = the Natars start to construct their World Wonder
24 hours / server speed = how long it takes (in hours) for the Natars to increase their World Wonder by one level