Once I saw a new player asking in the Gc whether it is a compulsory to join an alliance. So I thought why not just answer and I pm the dude. Thinking about that pm again, I found it too shallow. Nowadays being in a lonely alliance, I realize that the alliance could really help one grows. Here is one way.
Check out your Alliance Influence in the Alliance menu.
Influence Points is accumulated with the number of capitals your alliance own and the higher level the capital is the larger influence points collected. Higher level capitals are situated towards the centre of the map. So we could say that the more influential alliances will be able to conquer the central part of the map. Minor alliances will just have to be satisfied with the ones near the sea.
Influence points will help alliance at certain tier. In this example, the alliance with 260 points will her members gain advantage at certain percentage in building, income, army training and attack and a few more.
With only just 2 more capitals that could be conquered, this lonely alliance is just unable to go beyond 260 much. The open options are research at long, long period or just move into other more influential alliance and see if they accept you 😢