The Gamma Forests were a location inhabited by humans.
A girl from the Gamma Forests might be referred to as a 'Gamma Girl'. In the 52nd century, the Gamma Forests were 'Heaven-neutral', referring to its neutral stance towards recruitment for the Church. The people there crafted hand-stitched cloth symbols of devotion called 'prayer leaves'. These were embroidered with the names of one's children in the native tongue of the people of the Gamma Forests, as a sign of belief that their child would always come home to them.
A few facts were known of the Gamma Forests language. The word 'doctor' meant 'mighty warrior'. According to River Song, this was because of the history of the Doctor. The word for 'pond' was translated as 'river' because a river was the only water in the forests. A prayer leaf with 'melody' on it was translated to 'song', however the specifics of why were not known. (TV: A Good Man Goes to War)
The information known was related by or about one individual, Lorna Bucket. When she was a child, she met the Doctor in the Gamma Forests. She and her friend, Stefan, were nearly attacked by a creature, whose ship crash landed over the forest. The Eleventh Doctor led it away from them and connected a shield to a cable. The shield released an "impossibly bright" light, which engulfed the creature, who disappeared. Afterwards, he quickly gathered his equipment and departed in the TARDIS. (PROSE: Lorna's Escape)
Lorna claimed that the reason she enlisted in the Church was partly because the Doctor's visit to the forests was the only thing that had ever happened there. She wished to meet this "mighty warrior" again. Lorna later crafted a prayer leaf and gave it to Amy Pond, who had recently been separated from her newborn daughter. After the Battle of Demon's Run, as Lorna died, the Eleventh Doctor told her that he remembered her and spoke of how they had run. (TV: A Good Man Goes to War)