Some context: Alfred Cellier (1 December 1844 - 28 December 1891) was an English composer, orchestrator and conductor. In addition to conducting and music directing the original productions of several of the most famous Gilbert and Sullivan works and writing the overtures to some of them, Cellier conducted at many theatres in London, New York and on tour in Britain, America and Australia. He composed over a dozen operas and other works for the theatre, as well as for orchestra, but his 1886 comic opera, Dorothy, was by far his most successful work. It became the longest-running piece of musical theatre in the nineteenth century.
In 1885, Cellier composed a song, "There once was a time, my darling", for a piece produced by George Edwardes, Little Jack Sheppard (1885). Meanwhile he had composed what would become his greatest success, the comic opera Dorothy, with a libretto by B. C. Stephenson. To create the score, Cellier repurposed some of his music from his 1876 failure, Nell Gwynne, which had, nevertheless, received praise for its music. Dorothy had been announced for production at the Royalty Theatre in 1884, but ultimately Edwardes mounted it at his Gaiety Theatre on 25 September 1886. Cellier was in Australia from February 1886 to February 1887, conducting The Mikado and other Gilbert and Sullivan operas for the J. C. Williamson organization and was absent from London during the productions of The Carp, at the Savoy, and Dorothy. Neither the music nor the libretto of Dorothy initially attracted critical praise. The Times wrote, "Gentility reigns supreme, and with it unfortunately also a good deal of the refined feebleness and the ineptitude which are the defects of that quality." Stephenson rewrote the lyrics of one of Cellier's old songs, "Old Dreams" as "Queen of My Heart"; this helped the work to find success after it transferred in December to the Prince of Wales Theatre. The following year H. J. Leslie took over the production from Edwardes and introduced new stars, including Marie Tempest. Dorothy became an even greater success at the box office and transferred in December 1888 to the Lyric Theatre, built using the profits from the production, where it ran into 1889. Its initial run of a total of 931 performances was the longest of any piece of musical theatre up to that time, longer than even The Mikado, a fact that caused consternation to Cellier's friend Arthur Sullivan. Some critics reconsidered their earlier condemnation, the work became regarded as a classic Victorian piece, and the initially despised plot was traced seriously back to the Restoration playwrights David Garrick and Aphra Behn, and to Oliver Goldsmith and even Shakespeare. Its success led to revivals of some of Cellier's earlier works.  Cellier returned to Australia in 1888 to conduct Dorothy and made a final brief visit there for health reasons in early 1891, together with Stephenson. His last comic operas, Doris (1889, with Stephenson) and The Mountebanks (with Gilbert, produced in January 1892, a few days after the composer's death), were both modestly successful. Also after Cellier's death, Rutland Barrington used some of his music in his 1902 adaptation of Water Babies. Often in ill health throughout his life, Cellier was unable to finish The Mountebanks, and Ivan Caryll completed the score.  Cellier owed much to the influence of Sullivan. He was a fertile melodist, and his writing exhibited elegance and refinement, although he was not able to infuse his music with humour in the way that Sullivan did.  Cellier died at his home in Bloomsbury, London, at the age of 47. He was buried in West Norwood Cemetery.
Who or what is Dorothy?
A: Meanwhile he had composed what would become his greatest success, the comic opera Dorothy,
Some context: The Blackfoot Confederacy, Niitsitapi or Siksikaitsitapi (nitmowmeko, meaning "the people" or "Blackfoot-speaking real people") is a historic collective name for the four bands that make up the Blackfoot or Blackfeet people: three First Nation band governments in the provinces of Saskatchewan, Alberta, and British Columbia, and one federally recognized Native American tribe in Montana, United States. The Siksika ("Blackfoot"), the Kainai or Kainah ("Blood"), and the Northern Piegan or Peigan or Piikani ("Apa'tosee" or "Poor Robes") reside in Canada; the Southern Piegan/Piegan Blackfeet ("Amskapi Piikani" or Pikuni) are located in the United States, where they are also known as the Blackfeet Nation. In modern use, the term is sometimes used only for the three First Nations in Canada. Historically, the member peoples of the Confederacy were nomadic bison hunters and trout fishermen, who ranged across large areas of the northern Great Plains of western North America, specifically the semi-arid shortgrass prairie ecological region.
The Niitsitapi, also known as the Blackfoot or Blackfeet Indians, reside in the Great Plains of Montana and the Canadian provinces of Alberta and Saskatchewan. Only one of the Niitsitapi tribes are called Blackfoot or Siksika. The name is said to have come from the color of the peoples' moccasins, made of leather. They had typically dyed or painted the soles of their moccasins black. One legendary story claimed that the Siksika walked through ashes of prairie fires, which in turn colored the bottoms of their moccasins black.  Due to language and cultural patterns, anthropologists believe the Niitsitapi did not originate in the Great Plains of the Midwest North America, but migrated from the upper Northeastern part of the country. They coalesced as a group while living in the forests of what is now the Northeastern United States. They were mostly located around the modern-day border between Canada and the state of Maine. By 1200, the Niitsitapi were moving in search of more land. They moved west and settled for a while north of the Great Lakes in present-day Canada, but had to compete for resources with existing tribes. They left the Great Lakes area and kept moving west.  When they moved, they usually packed their belongings on an A-shaped sled called a travois. The travois was designed for transport over dry land. The Blackfoot had relied on dogs to pull the travois; they did not acquire horses until the 18th century. From the Great Lakes area, they continued to move west and eventually settled in the Great Plains.  The Plains had covered approximately 780,000 square miles (2,000,000 km2) with the Saskatchewan River to the north, the Rio Grande to the south, the Mississippi River to the east, and the Rocky Mountains to the west. Adopting the use of the horse, the Niitsitapi established themselves as one of the most powerful Indian tribes on the Plains in the late 18th century, earning themselves the name "The Lords of the Plains." Niitsitapi stories trace their residence and possession of their plains territory to "time immemorial."
Does any record exist of the Blackfoots' early  history  ?
A:
The name is said to have come from the color of the peoples' moccasins, made of leather. They had typically dyed or painted the soles of their moccasins black.