Final answer:
Queen Nzinga resisted European colonization by negotiating agreements, forming alliances, and waging war when treaties were broken, efforts that were sustained until she reached a peace treaty with the Portuguese in 1656.
Step-by-step explanation:
The factors that led to Queen Nzinga being able to resist European colonization between 1620-1640 include her initial agreement with the Portuguese, which allowed them limited trade rights without establishing forts, and her refusal to pay tribute to the Portuguese king. Additionally, she had the support of the common people and some of the nobility, as well as alliances with the kingdom of Kongo and at times, Dutch slave traders.
However, after Portugal began violating the treaty's terms, Nzinga encouraged enslaved people to escape and waged war against the Portuguese. Despite the Dutch making peace with the Portuguese, Nzinga continued her efforts to stop further European incursion into the African interior until she concluded a peace treaty in 1656.