George Catlin partnered with P. T. Barnum to set up an Indian show in Europe. It featured his paintings, some items that would be of interest to spectators (like weapons) and troops of Native American actors.
The group of Ioways was the second group to go. They left their homes (by then in Kansas) in fall of 1843 and arrived in London in July of 1844. They visited a number of cities, including Paris, and left in mid June of 1845.
Catlin published a book about the trip, entitled Catlin’s Notes of Eight Years’ Travels and Residence in Europe, with his North American Indian Collection. It was self-published in 1848. The book was in two volumes and the second volume is the one that describes Mahaska and his party.
The sketch and legend are from his book. I ran across another book called The Iowa, by William Harvey Minor. It was published in 1911 by The Torch Press in Cedar Rapids. This book includes a painting with no notice of who it is by or who is in it, other than the notation you can see below it.
Both books are digitized by Google and can be found with a search of the title.
I think the gentleman on the far right in the back is Jeffery Deroin, the interpreter. I am not sure who is in front on the right, but it could be George Melody.