In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Q: What was a tactic used?, Context: In some rare cases, such as with Ethiopia and Qing Dynasty China, the local governments were able to use the treaties to at least mitigate the impact of European colonization. This involved learning the intricacies of European diplomatic customs and then using the treaties to prevent a power from overstepping their agreement or by playing different powers against each other.
A:
playing different powers against each other