After joining an alliance, the other Alliance members will get an Alliance Chest every time you purchase Gold or a package. Tap ‘Alliance’ (P1) in the menu, then tap ‘Chests’ (P2) to find the Chests you contributed.
If you want to keep your Chests anonymous, you can turn on the function of ‘Anonymously Send Alliance Chest’. Follow the steps: Tap ‘More’ (P3) - ‘Settings’ (P4) – ‘Anonymously Send Alliance Chest’ (P5).