The genesis of the Kabbalah inside the Muslim world
As I told Stephan Beyer yesterday, this figure is (and his Arabic speaking circle in Baghdad are) who I consider to be the real founder(s) of what eventually became the sephirotic system of the Kabbalah we know today (i.e. the Tree of Life, four worlds, ten spheres, twenty-two paths, etc.) In his two articles i. Sefer Yesira and Early Islam: A Reappraisal and ii. Further Thoughts on the Origins of "Sefer yeṣirah", Steven Wasserstrom all but proves that the Sefer Yetzirah originated in Arabic speaking circles and is possibly a sort of redacted medieval Jewish reiteration of an Arabic translation of a work attributed to Apollonius of Tyana (Arabic 'Balīnus'), viz. sirr al-khalāʿiqa (The Secrets of Creation), wherein Abraham (ع) stands in for Apollonius as the author.
This thesis is not in any way dismissing or otherwise diminishing Jewish intellectual contributions to Islamic high culture, which are manifold. It merely posits that the sephirotic Kabbalah as a system is a neopythagorean-neoplatonic re-iteration/reinvention of Islamic Neoplatonism in Jewish guise and has no antiquity: Jewish mysticism and esotericism properly before the Kabbalah being the system of the Hekhalot which is a native Palestinian form of Jewish Gnosticism (capital 'G'). The influence of Hekhalot mysticism itself on the varieties of the early Ghulāt Shiʿism as well as (and especially) Islamic occulture and occultism are questions only now being explored by scholars, in this respect particularly by Gideon Bohak.
Comment: Maimonides was a dyed in the wool Avicennan. His Guide for the Perplexed was originally written in Arabic, and it is a thoroughly Avicennan work. His son Abraham was regularly hanging out with the Sufis of Cairo and basically became a devotee to the writings of Shihabuddin Yahya Suhrawardi, the Master of Illumination (d. 1191). Abraham Maimonides in turn was one of the sources for Joseph Gikatilla, who authored The Gates of Light (Sha'are Orah), which is practically a Jewish kabbalistic reiteration of Suhrawardi's Hikmat al-ishraq. Note that Gates of Light is the first systematic excursus upon the sephirotic Kabbalah as a system. This would make Suhrawardi one of the hidden intellectual sources for the whole kabbalistic system as we know it.