Ahmad ibn Fadlan ibn al-Abbas ibn Rashid ibn Hammad
Arabic jurist (of Islamic law) from Baghdad. In 922, during the reign of Caliph al-Muqtadir (Caliph 908-932), ibn Fadlan was sent on a mission to the Bulgars.
The Bulgar king, ibn Yatur, had sent a letter to the Caliph, requesting Islamic jurists to educate the Bulgars' jurists; aid in the construction of a mosque; and financial aid in the construction of fortifications in the south (against the Khazars).
The expedition left Baghdad, travelled over Tehran and Bokhara to the land of the Oguz, east of the Caspian Sea. Along the way, the monies intended for the Bulgar king were to have been collected from local tributary rulers. However, the money was not available, and ibn Fadlan's expedition arrived at the court of ibn Yatur without the expected gold. The king was not pleased, but did not blame ibn Fadlan for the misfortune.
During his stay at the Bulgar court, ibn Fadlan managed to educate (at least, according to his own report) the Bulgar jurists - however, he failed to convince them to observe five daily prayers in the direction of Mekkah, as opposed to the four which they were currently observing. He also failed to convince them that it was immoral for men and women to attend the same public baths simultaneously.
Upon his return (presumably in 923), ibn Fadlan wrote a treatise, usually called the Risala of ibn Fadlan (Risala is an Arabic word meaning inquiry or report - much like the Greek word Historia, in fact).
From the historian's point of view, the Risala is valuable not only for its description of the Bulgars, but also for the fact that ibn Fadlan encountered al-Rusiya (Rus, proto-Russian Nordic settlers in Slavic Russia) while he was at the Bulgar capital. In his Risala, ibn Fadlan describes the social customs, rituals and burial rites of the Rus. He also reports on some of the political aspects of Rus society, though this is based on second-hand information, not personal observation.
As an observer, ibn Fadlan is a product of his culture, and we are often treated to his own interpretations of the meaning of things. These are often coloured by his civilised distaste for the rough customs of the Rus:
"They are the filthiest of God's creatures. They have no modesty in defecation and urination, nor do they wash after pollution from orgasm, nor do they wash their hands after eating. Thus they are like wild asses. When they have come from their land and anchored on, or ties up at the shore of the Volga, which is a great river, they build big houses of wood on the shore, each holding ten to twenty persons more or less. Each man has a couch on which he sits. With them are pretty slave girls destined for sale to merchants: a man will have sexual intercourse with his slave girl while his companion looks on. Sometimes whole groups will come together in this fashion, each in the presence of others. A merchant who arrives to buy a slave girl from them may have to wait and look on while a Rus completes the act of intercourse with a slave girl.
Every day they must wash their faces and heads and this they do in the dirtiest and filthiest fashion possible: to wit, every morning a girl servant brings a great basin of water; she offers this to her master and he washes his hands and face and his hair - he washes it and combs it out with a comb in the water; then he blows his nose and spits into the basin. When he has finished, the servant carries the basin to the next person, who does likewise. She carries the basin thus to all the household in turn, and each blows his nose, spits, and washes his face and hair in it." (*)
(*) The events described in this last paragraph were used, largely unmodified, in the film The 13th Warrior, starring Antonio Banderas (screenplay by Michael Crichton, based on his book Eaters of the Dead). The film (and the book) are a nonsensical mish-mash of ibn Fadlan's narrative and the story of Beowulf. For all its faults as historical fiction, however, it does make an oddly entertaining film....go figure.