Sieges of towns and villages that were strategically valuable to military commanders was exceptionally common. Abyei and Bukavu were two such towns. Kisangani and Goma each overlooked supply routes used by the enemy, and Sierra Leone and Liberia were known to be rich in diamonds, giving invading commanders good reason to lay siege to them. The main theme of this passage is

When you’re answering the Paragraph Comprehension questions, keep these tips in mind:   
- Skim the passage and read the question. Then go back to the passage to find the answer. 
- Select the correct answer based on the passage rather than your personal knowledge or opinion on the subject.  
- Answer choices that include the word all, none, always, never, or some other absolute are rarely correct, so think twice before you settle on one of these answers.