The Jews came to the area after the Roman conquest of Palestine.
Even Wikipedia, lists Muhammed's tribe, the Quraysh as one of the Jewish tribes of Arabia.
Banu Qurayza — sub-clan of the al-Kāhinān, located in Yathrib(Medina), "principal family" fled Syria under Ghassanid rule, then fled Medina, after expulsion by Prophet Muhammed, back to Syria.
From the article, Before Islam, Medina Was Originally A Jewish City
Although the fact is little publicized, the Arab world’s second holiest city, Medina, was one of the allegedly “purely Arab” cities that actually was first settled by Jewish tribes. 1 History shows that Judaism was already well established in Medina two centuries before Muhammad’s birth.
On page 40, of his book “Arabs In History”, Bernard Lewis writes:
“The city of Medina, some 280 miles north of Mecca, had originally been settled by Jewish tribes from the north, … The comparative richness of the town attracted an infiltration of pagan Arabs who came at first as clients of the Jews and ultimately succeeded in dominating them. Medina, or, as it was known before Islam, Yathrib, had no form of stable government at all. The town was tom by the feuds of the rival Arab tribes of Aus and Khazraj, with the Jews maintaining an uneasy balance of power. The latter, engaged mainly in agriculture and handicrafts, were economically and culturally superior to the Arabs, and were consequently disliked…. as soon as the Arabs had attained unity through the agency of Muhammad they attacked and ultimately eliminated the Jews.”
The number of Jews in Medina swelled following the Roman invasion of Israel – the subsequent expulsion of its Jewish population, and from Jews fleeing persecution in Persia2. These refugees were assimilated into the three major Jewish tribes in Medina: the Banu Nadir, the Banu Quynuqua, and the Banu Quraiza. When these Jews resettled in Medina, they took with them a superior knowledge of agriculture, irrigation, and industry. Homeless Jewish refugees in the course of a few generations became large landowners in the country. In addition, the refugees who had come from Israel quickly became the controllers of its finance and trade. This new Jewish prosperity also quickly became a direct challenge to the Arabs of the region, particularly the Quraysh at Mecca (of which Mohammad was a member) and other Arab tribes in Medina.
According to Alfred Guillaume,
At the dawn of Islam the Jews dominated the economic life of the Hijaz [Arabia]. They held all the best land … ; at Medina they must have formed at least half of the population. There was also a Jewish settlement to the north of the Gulf of Aqaba…. What is important is to note that the Jews of the Hijaz made many proselytes [or converts] among the Arab tribesmen.5
“The More we go to Hajj and Umrah the more Muslim will get killed with that money! The Banu Qaynuqa (also spelled Banu Kainuka, Banu Kaynuka, Banu Qainuqa, Banu Qaynuqa, Arabic: بنو قينقاع) was one of the three main Jewish tribes living in the 7th century of Medina, now in Saudi Arabia. In 624, they were expelled during the Invasion of Banu Qaynuqa, by the Islamic prophet Muhammad for allegedly breaking the treaty known as the Constitution of Medina.”
From the article, Medina, Islam's second holiest city, was originally a Jewish "settlement"
Bernard Lewis writes:
The Quraysh Rebuild the Kaba
The city of Medina, some 280 miles north of Mecca, had originally been settled by Jewish tribes from the north, especially the Banu Nadir and Banu Quraiza. The comparative richness of the town attracted an infiltration of pagan Arabs who came at first as clients of the Jews and ultimately succeeded in dominating them. Medina, or, as it was known before Islam, Yathrib, had no form of stable government at all. The town was tom by the feuds of the rival Arab tribes of Aus and Khazraj, with the Jews maintaining an uneasy balance of power. The latter, engaged mainly in agriculture and handicrafts, were economically and culturally superior to the Arabs, and were consequently disliked.... as soon as the Arabs had attained unity through the agency of Muhammad they attacked and ultimately eliminated the Jews.
From The Jews of Arabia
“Arab historians mention some 20 Jewish tribes, including two tribes of Kohanim. The Jews spoke Arabic, were organised into clans and tribes just like the Arabs, and seem to have fully assimilated the values and customs of desert society. “
Arab sources maintain that the Jews of Medina were survivors of the Jewish revolt against Rome.
Another theory is that the Jewish date-growers - and the cultivation of dates was the most common occupation - might have come from the Jordan valley as refugees from Christian Byzantine persecution. Another obvious source of immigrants was, of course, Babylonians.
The Jews were engaged in agriculture, not trade which was exclusively in the hands of the Arabs. According to Arab legends, Jews introduced the date palm and the honey bee into Arabia. Also, advanced irrigation and other new agricultural crafts. The Jews appear to have been educated. It was their ability to read and write that made Bible stories and Midrashim generally familiar to the pagan Arabs - and those were the seeds from which Islam developed.
From “Massacre in Medina,” Segula Magazine, issue 3.
The Jewish community of northern Arabia was one of the largest ancient Jewish communities in the history of the Jewish people.”1
They were powerful and wealthy. They were respected by the local Arabian tribes for their religion, culture, erudition, and literacy. They built castles on mountaintops and developed productive plantations. They had military prowess, horses, and advanced weaponry. And they were almost totally annihilated in the short span of a few years. Their story should make every Jew shudder.
The Jews of Medina were divided into three groups: The Banu Qaynuqa were blacksmiths, weapon wrights, and goldsmiths. The Banu Nadir had date plantations. The Banu QurayUa were wine merchants. These groups often quarreled. Sometimes the hostility among them broke out into actual fighting.”
In The Jewish Kingdoms of Arabia 390-626 CE Decimated by the rise of Islam:
The origin and previous history of these Jews is unclear, but they may have arrived shortly after the destruction of the Second Temple. They formed three main communities, Banu-Lnadir, Banu Kainuka, and Banu Kuraiza, who occupied themselves mainly with the cultivation of palm-groves but also exercised other callings….
“BANU KURAIZA: One of the three Jewish tribes in MEDINA. They inhabited several villages to the S of the town, and their main occupation was agriculture. “
It is in the Quaraish language that the Quran was written,
“He then commissioned Zaid, in conjunction with three members of Muhammad's own tribe, the Quraish, to produce a recension of the work. At least this is what his language seems to imply, for he said to the three Quraishites, "Whenever ye differ, ye and Zaid ibti Thabit, in reference to any part of the Qur'an, then write it in the dialect of the Quraish, for it was revealed in their language." (source: The Original Sources Of The Qur'an Its Origin In Pagan Legends and Mythology By W. St. Clair Tisdall, M.A., D.D., 1905 AD )
“It was the tribe that took care of the sacred Ka’bah, or house of worship, and gave water and food to pilgrims who visited it. The Quraysh tribe is one of three Jewish tribes at Mecca.
The Quraysh was divided into 10 clans.2 The Prophet (SAW) and his family hailed from the Hashimi clan, but the most powerful clan within the Quraysh was the Umayyad, whose most famous member was Uthman.”
From the book, MUHAMMAD his life based on the earliest sources, page 41 (Islamic Bulletin):
“… when Muhammad was thirty-five years old, Quraysh decided to rebuild the Ka'bah. … But such was their awe of the Ka'bah that they hesitated to lay hands on it….