The Talmud describes a fascinating exchange between the Roman Governor in Palestine during the second century CE and the great Jewish sage, Rabbi Akiva. The Romans, like the Greeks, could not appreciate the concept of Shabbat in which one would allow all slaves a “day off” from labor. They believed that the Jews created Shabbat out of laziness.
“What makes this day different than any other day?” the Roman Governor Turnus Rufus asked Rabbi Akiva. In brilliant and brazen sarcasm, Rabbi Akiva responded: “What makes you different than any other person?” “The Emperor has so willed.” He answered, “He bestowed upon me special honor.” Rabbi Akiva replied: “Well, the Emperor of the world has chosen this day [Shabbat] as a unique and holy day, bestowing upon it special honor.” The Roman Governor continued to question Rabbi Akiva, “But perhaps you have confused the days? How are you sure that in all this time you have not misplaced the seventh day”? “The river Sambatyon will prove it!” responded Rabbi Akiva.
Rabbi Akiva was referring to a legendary river named Sambatyon (which means Shabbat in Greek) which is located either in Syria, Afghanistan or Ethiopia. This river was unnavigable on weekdays because it flowed with currents carrying along stones with tremendous force, but it rested on the Sabbath.
A Roman historian living in an era prior to Rabbi Akiva, Pliny the Elder (AD 23– AD 79), described the river in his work “Natural History.” He writes that the river ran rapidly for six days in the week and rested on the Shabbat.
An Ashkenazi Jewish tradition speaks of the Lost Tribes as Die Roite Yiddelech, "The little red Jews", cut off from the rest of Jewry by the legendary river Sambatyon "whose foaming waters raise high up into the sky a wall of fire and smoke that is impossible to pass through”.Ovadiah ben Avraham, also know as the Bartenura, writes that he was informed by Adeni Jews in Jerusalem, that they had heard from Muslim merchants that the river was located about a five days' journey from Aden, a seaport city in Yemen. The river, which flows with rocks for six days a week, completely surrounded a land inhabited by Jews who could not ever leave, for by doing so, Shabbat would be desecrated. These Jews were all the offspring of Moses and were as holy as angels and sinless.