In short, most everything about the historical Muhammad is a back redaction emerging with the Abbasid dynasty. The former Umayyad dynasty relied more or lest upon the ratification of the Medina Constitution, signed in 622. A treaty of alliance between different factions of Arabs, of Christians, Hanifs (Sabians), and messianic Jews.
That's preciously what I think what happened.
When the Arabs conquered Persia (641), they found a strong Jewish community in Isfahan. The Arab chronicler Abu Nuʿaym reported that at that time the Jews were celebrating, dancing, and playing music in expectation of a "Jewish king." Under the caliphate, the Jewish quarter in Isfahan, known as Jayy, had grown to such a degree in number and size that Arab and Persian geographers called it al-Yahūdiyya, "the city of the Jews."
There's no evidence for the worship of a Ka'aba in pre-Islamic history and the Arabic word Ka'ab indicates any cube, or a protuberance out of something plain.
There is now strong evidence for pre-Islamic to pilgrimage to Petra.
The combination of classical historiography, ethnography, epigraphy and the archaeological record, interpreted at the light of cultural astronomy strongly supports the idea of a Nabataean calendar centered in the cult of their deities and their ancestors framed within the Babylonian lunisolar calendar of the Seleucid Empire, but not fully restricted by it since the Nabataean calendar seems to have started in Nisan.
- New Year’s Eve on 1 Nisan;
- Full Moon after Spring Equinox (14 Nisan), in a clear parallelism to Jewish Passover;
- 1st Crescent after Spring Equinox (1 Nisan – New Year’s Eve − or 1 Iyyar);
- 1st Crescent after Summer Solstice (1 (B)ab);
- Heliacal Rising of Sirius (Isis) in c. 20/7 Julian. Hence in (B)ab.
- 1st Crescent after Autumn Equinox (1 Tishri);
- Aggathalbaeith in the 1st Lunar Month after Autumn Equinox (most likely Tishri);
- Winter Solstice and the Birth of Dushara, as celebrated during the Epiphany in late Roman times;
- 1st Crescent or Full Moon of Thebet, the lunar month after, or including, the Winter Solstice.
These dates would have been the moments for main festivals and celebrations which, in at least three occasions − the two equinoxes and the winter solstice − would have been performed in the form of ritual pilgrimages at attractive sacred spots in the vicinity of the city such as AdDeir (and the Lions’ Triclinium), the high-places at Jabal Madbah and Jabal Khubza, or the summit of Jabal Hārūn proper.
This approach has its limitations but with Dan Gibson's geographical analysis of hadith it is possible to reconstruct the pre-Islamic Hajj.
The proposed pilgrimage route based upon pre-silamic references and ahadith
From Mina (Modern Wadi Misa, Nabataean Gaia) through Bakkah (West-Aramaic for gorge) and Colonnade Street passed the Masjid Haram of Petra (msg hrem), the temple of Qasr al-Bint with its temenos, and then the trail towards the mountain plateau where the Monastery (Ad-Deir) was sculpted on the sandstone cliffs and al-Bayda.
Since the Abbasid dynasty emerged from Harran, we find much more Chaldean influences than let say Judaic influences in the Koran.
The Harran is also the division between the Petraean and Palmyran-Saific version of the Nabataean religion: Hellenized versus a more ascetic version. The move from Harran to Bagdad is another essential key.