A children's burial ground filled with the remains of Native American infants is providing archaeologists with a new wealth of information about the first residents of North America.

The Upward Sun River site in central Alaska is the location of one of the oldest-known burial grounds in North America. The first remains found there were the cremated ashes of a three-year-old boy who perished around 11,500 years ago, discovered in 2010. In late 2013, archaeologists uncovered the graves of an infant who died shortly after birth, as well as one who lived for approximately 12 weeks. The two more recent finds were well-preserved, allowing a high-precision DNA analysis. Researchers are uncertain whether or not the newborns, who were buried in the same pit, were related to each other.

"The most exciting thing is going to be the genetics. There's still a question here as to exactly who these people are at Upward Sun River," John Hoffecker from the University of Colorado, Boulder, an archaeologist not involved in the findings, said.

These ancient societies did not possess a written language, and graves from the end of the last major Ice Age are rarely preserved. Together, these factors make it difficult for researchers to study the funerary practices of Stone Age cultures.

"These are new windows into these ancient peoples' lifestyle," Ben Potter, from the University of Alaska told the press.

Weapons and other artifacts, including shafted bifaces, similar to spears made of stone and antler, were found buried along with the infants. These bodies, discovered just 15 feet under the ashes found in 2010, are the youngest bodies ever found in Arctic regions of North America.

Spears buried along with the children could reflect the importance that the ancient people of the region placed on the hunting tools. Rituals around death and how these ancient societies viewed the end of life could be better-understood by archaeologists by examining the skeletal remains, as well as the goods buried with the infants.

"The presence of two burial events - the buried infants and cremated child - within the same feature could indicate relatively longer-term residential occupation of the site than previously expected. The remains of salmon-like fish and ground squirrels in the burial pit, meanwhile, indicate that the site where the burial took place was likely occupied by hunter-gatherers between June and August," the National Science Foundation, which helped fund the research, stated in a news release.

Potter's team worked closely with native tribes in the area, as they excavated the graves, respecting their laws and traditions.

Discovery of the infant's graves and analysis of what they can tell researchers about ancient society was profiled in the Proceedings of the National Academy of Sciences (PNAS).