It's just weeks after the war between the humans and the Na'vi. Several of Parker's people stayed behind to help rebuild the Omaticaya's home and to learn the ways of the Na'vi. Neytiri took the humans under her wing and allowed the Na'vi to show the humans their ways.
A few of the humans questioned Neytiri about becoming Na'vi themselves. Most of the scientists stayed behind, including Grace's personal assistant so Avatar's were in the process of being made. Several of the soldiers stayed behind as well due to Jake and Norm staying behind.
The humans and the Omaticaya slowly became a family. A family that was soon going to be ripped apart. A few of the Omaticaya's left the clan because of the humans. They didn't want anything to do with them. This started a tension between the Na'vi clans. Some were willing to work it out with the Omaticaya while others just wanted the humans gone.
There was one, the Tipani Clan, the closest clan to the Omaticaya, who disagreed most with the humans being there. They warned Neytiri that with the humans remaining on Pandora their allegiance would be over. Neytiri knew in her heart that the humans needed to stay on Pandora so that the clans and the humans could all better themselves.
Without the humans remaining, the bond's they had made would be broken. There would be no more understanding between the Na'vi and the humans, but the Tipani clan refused to listen to Neytiri and began preparing for war.