Events in Uncharted 2: Among Thieves
The camp was set up by Lazarevic in Borneo whilst he was searching for the Lost Fleet and the Cintamani Stone. Nathan Drake, Victor Sullivan and Chloe Frazer sabotage the base during the events of Uncharted 2: Among Thieves. Chloe, working undercover, sets up charges around the camp in which Drake and Sully activate. This causes a distraction to Lazarevic and his soldiers. This is when Nate and Sully attack the main area of the camp and search through the documents that Lazarevic had there.
In the middle of the camp is a large room filled with Marco Polo's journals. Surrounding it are walkways and a tower armed with a machine gun. Around this section of the camp is the jungle of Borneo, although there are several smaller camps dotted around, all filled with soldiers.