Question

How did the Tang Dynasty earn the "Mandate of Heaven" and
then lose it?

Answer 1

Military defeats, rebellions, and economic troubles all happened which caused the Tang Dynasty to loose the Mandate of Heaven.

Step-by-step explanation:

Answer 2

DONT CLICK ON ANY LINKS!!
If a king ruled unfairly he could lose this approval, which would result in his downfall. Overthrow, natural disasters, and famine were taken as a sign that the ruler had lost the Mandate of Heaven. ... The Mandate of Heaven did not require a ruler to be of noble birth, and had no time limitations.