Had Sufism already been established in the true teachings of Islam way back before the different sects were broken off and that we observe in this current age?
Thank you for your question. Spirituality is an essential aspect of the source literature (which are the bases of the true teachings of Islam), however, the term Sufism remains loosely defined in western scholarship and it has been the subject of much discussion.
The term invokes a specific reading of the history of mysticism, its theology, its institutions and its practices and it can be argued that it is a predominantly Sunni account of spirituality in the Muslim world. Discussion of the sources of this tradition was an important question in the early study of Sufism and while some scholars claimed that the sources of Sufism were outside of the scriptural sources, others argued that they were rooted in them. The second opinion became more acceptable and early Companions of the Prophet (saw) were referred to as proto-Sufis, signifying that the Sufi tradition was a later development, while its sources firmly originated in Islam.
Juxtaposing Shi'i to Sufism (Shi'i Sufism) may adequately describe some Shi'i expressions of Sufism, and indeed the term irfan was used by some seminarians in Iran to distinguish a tradition acceptable to the traditional seminary, different to these forms of Shi'i Sufism. The importance this form of irfan places on the divine law and its inner aspects, as well as in the more complex aspects of tawhid and walayah ensues that it provides a strong reading of the scriptural sources. It has also been argued that the Shi'i source literature has a mystical aspect of its own and is, therefore, the impetus of its own form of spirituality.
May you always be successful.