Restoring the timeline is of utmost importance, and to do that, Ages need to flourish! However, you don't need to spend all of your resources and people at once. Tapping on the buy multiplier in the top right corner will toggle between x1, 1%, 10%, 50%, and MAX.
To toggle the Buy 1% option on or off, tap on the settings icon (top right).
No matter what you choose, your contribution will be remembered throughout the ages!