What is one factor that has led to increased conflict and division in some areas in the Middle East

The growth of radical Islamic fundamentalism.

Explanation:

The one factor that has led to increased conflict and division in some areas in the Middle East is the growth of radical Islamic fundamentalism.

Muslims who become a part of it are thought to get involved in terrorist activities. Because such Muslims who showed their keen interest in Islamic fundamentalism are mostly influenced to make it more like a religious war so that their religion can grow.