The word 'Uwaysi' designates a Muslim mystic who looks for instruction from the spirit of a dead or physically absent Saint. It is derived from the name of a legendary Companion of the beloved Prophet Muhammad (Allah bless him and give him peace), Hazrat Uwais (may Allah be pleased with him), who is supposed to have communicated with the Prophet by telepathy. Usually there are isolated references in Islamic literature, but around 1600 CE one Ahmad of Uzgen in what is now Kirghizia [in ex-Soviet Central Asia] wrote a History of the Uwaysi, in which he presented an evidently imaginary brotherhood as flourishing from the 7th to 14th centuries. Much of this 'history' is set in East Turkistan (now Xinjiang in north west China). [Source: Imaginary Muslims - The Uwaisi Sufis of Central Asia by Julian Baldwick]
An Uwaisi, then is a dervish [literally 'poor people' but came to mean 'people of the spiritual life'] who apparently has no elder instructor or physician for his soul, but claims to receive guidance from the beloved Prophet Muhammad (Allah bless him and give him peace) or some other invincible teacher.
The trans-historical character of Sufi initiation seriously undermines the conventional understanding of tradition. The model of this kind of relationship was Uways al-Qarani, a contemporary of the Prophet Muhammad (Allah bless him and give him peace) who never met the Prophet, but was nevertheless an adept saint, deeply devoted to the Prophet. This kind of internal relationship, called Uwaysi initiation, shows up in a number of well-known Sufi lineages. In this way Abu al-Hasan Kharaqani (may Allah be pleased with him) [d.1034] was initiated by the spirit of Bayazid Bistami, and this is accepted as a standard link in the Naqshbandi chain of Masters. There are in addition a number of famous Sufis who have been initiated by the deathless Prophet Khidr. The power of this kind of trans-historical transmission is was so great that at certain periods, one finds mention of an Uwaysi [or Uveysi] order as if it were another standard lineage. What is remarkable about this formulation is that it preserves the historical form of the initiatic genealogy while completely somersaulting over the need for external physical contact. [The Shambala Guide to Sufism by Dr. Carl W. Ernst]
The Uwaisi tradition acquired a new significance from the 14th century onwards, with the foundation of the Naqshbandi brotherhood. Kwaja Baha' al-Din Naqshbandi himself is recorded as having not only a living master, one Kwaja Kulal [d.1371], but also a dead Uwaisi elder, Kwaja Abd al-khaliq Ghujdawani [d.1179-80]. Before Naqshband there had been a line of 'Masters' [Kwajagan].
In the 17th century, one important Uwaisi was Kwaja Ahmad Sirhindi [1564-1624], who was born in the city of Sirhindi, in northern India. He was both a Naqshbandi and an Uwaysi. Thus, he explained, he was a discipleof Prophet Muhammad (Allah bless him and give him peace) via intermediaries in the Naqshbandi brotherhood. However, after studying with a Naqshbandi elder he became an Uwaysi, apparently in the sense of no longer having any visible instructor. Although he was an Uwaysi, he declared, he did have an instructor: Almighty Allah himself [a similar claim of being instructed by Allah was made by Kharaqani]. Thus he was also a co-disciple of Prophet Muhammad, having the same divine teacher. Although he was a 'Follower' ['Tabi'], in a sense of coming after the Prophet, he sat at the same table as the Prophet, like a servant sharing food with the master, invited by Him.
From the 18th century onwards the most significant Islamic thinker Shah Wali Allah of Delhi [1703-62], puts forward a theory of types of 'relationship' [nisba] with Almighty Allah: each Sufi brotherhood has its goal the acquisition of a special relationship with Almighty Allah, peculiar to that brotherhood. He says that the relationship of the supposed founder of the Qadiri brotherhood, Shaikh Sayyiduna Abdul Qadir of Jilan in northern Iraq [d.1165],was the relationship of the Uwaysi-hood: this gives information about how Almighty Allah rules the universe, and by it links are formed with the spirits of Sufi elders and Prophet Muhammad.