Ruby is located on the south bank of the Yukon River, in the Kilbuck-Kuskokwim Mountains. It is about 50 air miles east of Galena and 230 air miles west of Fairbanks.

Ruby's residents are Koyukon Athabaskans of the Nowitna-Koyukuk band, a nomadic group who followed game with the changing seasons. Ruby developed as a supply point for gold prospectors. It was named after the red-colored stones found on the riverbank that prospectors thought were rubies. Two gold strikes, one at Ruby Creek in 1907 and another at Long Creek in 1911, attracted hundreds of prospectors to the area, but after the gold rush, the population declined rapidly. A post office was established in 1912, and Ruby incorporated as a city in 1913. In 2011, the Alaska Department of Labor estimated the population to be 173. A federally recognized tribe is located in the community, the Native Village of Ruby. The traditional Athabaskan culture and subsistence practices are the focal point of village life.

Mass was first celebrated in August 1912 by a missionary priest of the Society of Jesus in the home of Mr. Henry Lovely. In September of that year, The priest baptized the first boy born in Ruby. The following month the priest bought a lot with a one story frame building on it, which he converted into a church and priest quarters. Ruby's parish was placed under the patronage of Saint Peter the Apostle. In more recent years the church has been known as Saint Peter in Chains. The makeshift building served until a new church was built in 1948, which has been added onto and adapted considerably over the years.

Ruby has seldom had a priest in residence. It was served by visiting priests, mostly of the Society of Jesus, visiting from other villages, including Tanana, Nulato, Galena, Kaltag and Saint Marys. Diocesan and Columban priests have also visited. Franciscan Fr. Joseph Hemmer, O.F.M., stationed in Kaltag, has visited on a regular basis since 1994 and continues to do so.

The mission has also been served by a Xaverian Brother and by Religious Sisters of various Orders, notably the Sisters of St. Dominic; Sisters of Notre Dame; and Sisters of Providence.