How did the alliance between Ousamequin's people and the Pilgrims help each
group? *

friendly and mutual relationship between the natives and the settlers of Plymouth Bay.

Explanation:

The alliance treaty between Ousamequin of the Wampanoag confederacy and the Pilgrims was one of the first treaties signed between the setters and the natives of America.

The Treaty of Wampanoag which was signed in the year 1671 was a peace treaty that included the agreement not to harm or attack each other but to live in mutual understanding. It also included that each party would help the other party when threatened by third parties.

It secured a friendly and mutual relationship between the natives and the settlers of Plymouth Bay for more than 50 years.

i believe your answer is mountains.