In the article about Alchemy I wrote that the upcoming religion of the Islam brought a saveguard for many western occultist that had to flee the rage of Christianity. After the destruction of Alexandria and in particular it’s libraries, many alchemists, hermeticists, gnostics, Jews, etc. fled to the regions where soon the prophet Mohammed would start his quest. The ‘pre-Muslims’ and later the Muslims treated the immigrants with respect and both parties learned a lot from eachother.
When the Muslims reigned southern Europe a fruitfull environment for mysticism and occultism existed in Spain. Muslims brought alchemical and hermetic texts that had come to them by the fleeing occultists of 1000 years earlier and translated them (back) in western languages.
There were also many Jews in Spain and the Jewish alchemist Moses ben Maimon (1135-1204 better known as Maimonides) compiled the text that we now know as the Mishnàh. This word means ‘repetitions’ and the text contains explanations of the Thorah. It seems that Maimon was a re-compiler or maybe only a translator, because the second century Rabbi Judah ha-Nassi is (also) regarded as the compiler of the Mishnàh. The Thorah are the first five books of the Jewish bible (the Old Testament of the Christians) and the word means ‘doctrine’.
Moses of Léon (1250-1305) wrote (or compiled) a large book about the Thorah that we came to know as the Sepher Zohar or the ‘book of splendour’. This book claims to be the writings of a second century wiseman and is mostly regarded the most important Kabbalistic text that contains every aspect of the tradition (which is the translation of the word Kabbalah by the way). 
There are even people who claim that Kabbalism came into being in this time and with the Zohar, but not everybody agrees with this.
Another major Kabbalistic text that originated in the Muslim environment in Spain are the Sepher Yetzirah or ‘book of creation’ which describes the ten emanations of god, or the “sephiroth” and however it does not give the drawing, describes the well-known ‘tree of life’ (see left and particularly the article “Etz Chayyim”).
However there are people who say that Kabbalism originates in this 12th century climate, this is not entirely true.
The Hebrew characters for the word are 
, qof-beth-lamed-heh, or 
, kaf-beth-lamed-heh from right to left. Since ancient Hebrew doesn’t have any vowels and the consonants can be transcribed to our letters in different way, there are many ways of writing the word. I usually use “Kabbalah”, but it may just as well be “Kabala”, “Cabala”, “Qabala”, “Quabalah” or even “Quobele” if you like (we also don’t know how ancient Hebrew was pronounced). It is generally accepted that there are two kinds of Kabbalah, the speculative Kabbalah or ‘Jehunieth’ and the practical Kabbalah or ‘Maassieth’. The first is of course of a more philosophical nature, the second is involved with magic and Jewish word-games (“Gematria” and Notaricon”, maybe enough to say about them for a separate article). Kabbalah is mostly based on the ancient Jewish texts, such as the Thorah, the Talmud (‘instructions’), Mishnah, Gemarah (supplement to the Mishnah), etc., but mostly on the Thorah.
Written in Hebrew the Thorah contains text and numbers, since every Hebrew character is also a number. When you count the value for a certain word or piece of the text, other words with the same value are closely aligned (this is actually “gematria”). This is an example of practical Kabbalah on the Thorah.
When speaking of God, there is a striking similarity with the gnostic worldview. Kabbalists say that the God from the Bible isn’t the highest God, but a creator-God. The highest Divinity is endless, eternal, unlimited and uncomprehendable and named “En-Soph”. The Sephirotic tree is a schematic reproduction of creation. En- Soph is above and all around and the 10 sephiroth are as said 10 emanations of It. The tree can be splitted in three parts of which the top three sephiroth form the highest of the three worlds, the next three sephiroth the second highest, the next three the third and the last sephiroth “Kliphoth” (“hell” so to say) or the material plane.
Of course there is a lot to say about this, but that is not really the purpose of this article.
Jewish mysticism is mostly based on the vision of Esechiel from the Old Testament. The tradition is called “Merkavah mysticism” that developped for a long long time until a new impulse came in the 12th century Spain and ‘real Kabbalism’ came forth. Kabbalism quickly spread through the Jewish world, but also the west got infected. Western occultists and in particular Ramon Lull (1235 – 1315) and the Italian school of Cosimo de Medici (1389 – 1464) gave birth to the “Christian Cabala” that is mostly written like this to divide it from the orthodox Jewish Kabbalah (and later the ceremonial magical (Crowlegian) Qabalah), which is of course based on the Jewish Kabbalah, but with more astrological and western esoteric influences. These two developped quite seperately from eachother, especially after the time that the Christians reconquered southern Europe from the Muslims and both the Muslims and the Jews were killed or driven out. What we here in the west mostly get is (fairly) Christian Kabbalah and the serious Jewish literature is mostly unavailable in western languages. Still it is an extremely interesting field for investigation, probably enough to fill a life-time.