If joining an existing Alliance doesn't interest you, you can always create your own Alliance. Creating your own allows you to customize the banner, description and language of an Alliance. 
To create an Alliance, first, make sure you are not already a member of an Alliance, then just tap the Alliance icon on your screen. Choose the "Create" tab and start customizing! Please note, it requires fifty (50) Gems to create an Alliance so consider your decision carefully. Once your Alliance has been created, you can change the description, badge, etc. by using the Settings tab on your Alliance page but keep in mind, all Alliance names and descriptions must comply with our Chat Rules & Guidelines and Terms of Service.
Please note - if you are the only member of your Alliance and decide to leave, the Alliance will be deleted and you will not be able to return. If you do leave or change an Alliance, the Wanted Titan Chest will go on 12-hour cooldown.