It is said that long before Humans arrived on the planet of Naboo circa 3900 BBY, the native sentient inhabitants, the Gungans, engaged in war against the bursas. These bursas were a savage, semi-sentient species that routinely assaulted Gungan settlements. As a response to this danger, the Gungans advanced their military capabilities and established the Gungan Grand Army, which supposedly eradicated the bursas, leading them to extinction. This conflict with the bursas resulted in a more militarized and tribal Gungan society. The Gungan Grand Army was maintained in subsequent years, even during times of peace. Bursas remained a factor in the war among the Gungan tribes, which concluded in 3000 BBY. Later, members of the Amaran species captured and bred them for export.
The Gungan-bursa war was initially referenced within the Gungan DataBank entry of the 2001 LucasArts video game titled Star Wars: Galactic Battlegrounds. The original idea for this war came from Star Wars creator George Lucas, who envisioned the Gungan Grand Army as being formed to battle creatures resembling bears. Author Daniel Wallace discovered Lucas's concept and planned to elaborate on it within The Essential Guide to Episode I. He commissioned artist Robin Pronovost to design the creatures that became known as the bursas, although the guide was ultimately never published. In a blog post featuring concept art of a bursa drawn in 2000, Pronovost provided an unofficial explanation, stating that the Gungans drove the bursas to extinction, but the Amarans preserved them through a breeding program.
The 2001 reference book The Essential Guide to Alien Species presented a contradiction to Galactic Battlegrounds, indicating that the Gungan Grand Army was established during a conflict with unidentified invaders of Naboo in their early history. Furthermore, 2006's The New Essential Guide to Alien Species claimed that the conflict occurred almost 100 years prior to the Battle of Yavin. Another inconsistency can be found in the 2002 forty-seventh edition of The Official Star Wars Fact File magazine, which asserted that the Gungan Grand Army was formed by united factions following the war between the Gungan tribes. This article relies on sources that attribute the formation of the Gungan Grand Army to the war against the bursas, including Galactic Battlegrounds, 2008's The Complete Star Wars Encyclopedia, and 2009's The Essential Atlas.