Omanga is both the most northern and largest territory illustrated by Bob in his notebook map. We learn from his experiences that Omangans soon after World War II began using nuclear reactors to provide energy making them a rich, advanced and powerful state.
Some evidence suggests that Omanga overlooked their fossil fuel resources altogether and began developing nuclear power as soon as possible, building 3 operational power plants. Due to unknown circumstances their most northern 1st generation plant exploded spewing a large amount of radioactive particles into the air. This contamination spread to most of the surrounding area, the north eastern region of Omanga and into the neighbouring state of Gafia. A tertiary wave of less harmful toxins spread further than the initial contamination zone, these areas are possibly not immediately lethal but can cause radiation poisoning after prolonged exposure. All of the areas affected by the explosion are uninhabitable with no plan or animal life.
The power plant disaster had grave consequences for all of Omanga as citizens living in the north quickly fled to more southern settlements seeking aid and shelter. With a massive strain on resources the Omanga government took an swift action and organised invasions into the nearby weaker states of Gafia and Agurts. These actions have tainted Omanga with an "aggressive bullish" attitude but an argument could be made that they are simply attempting the best course of action for survival by utilising their strengths in desperate times.
The more peace orientated government of Gafia were initially horrified by the radiation damage to their northern borders cutting off valuable trade routes and were unprepared for the subsequent Omangan invasion from the west. This meant that the Gafian leadership had to bow to the stronger force, introducing an appeasement policy of both political influence and material possessions. The border based Gafians fighting against the invasion ignored the decisions of their government and continue to protect their land and property in a number of long and indecisive skirmishes.
In the 4th Quarter of 2014, Acid Rain World creator Kit Lau revealed he was in development of 20 new characters one of these was revealed as an Omangan soldier. No details or prototypes of this figure has been released.