This link above is to a very good article about Junaid Baghdadi (ra) and his life. He is one of the most important influences in early Sufism. What is mentioned here is only a portion of the information at that website.
HIS POSITION IN THE SILSILA : Sheikh alal Itlaaq, Qultbul Istihqaaq, Mamba-e-Israar, Sultan-e-Tariqat, Sayyidut Taaifa, Hazrat Sheikh Junaid-e-Baghdadi (radi Allaho anhu) is the eleventh Imam and Sheikh of the Silsila Aaliyah Qaaderiyah Barakaatiyah Razviyah Nooriyah.
When he was seven years old, he went to Haramain Sharifain in the company of Hazrat Sirri Saqti (radi Allaho anhu). When they reached the Haram Shareef, four hundred Ulama were seated there, discussing the topic of Shukr (Gratefulness). All of the Ulama presented their views during this sitting. Hazrat Sirri Saqti (radi Allaho anhu) then turned to Hazrat Junaid-e-Baghdadi (radi Allaho anhu) and said, “O Junaid! You too should say something.” He lowered his sight for a few moments, and then said, “Shukr (gratefulness) is this, that you should not be disobedient through whatever bounties Allah has blessed you with, and you should not use it as a means of disobedience and causing distress.” On hearing this, all the Ulama said together, “O Coolness of our Eyes. Whatever you have said, is the truth and you are honest in your words, and we cannot say better than what you have said.” Hazrat Sirri Saqti (radi Allaho anhu) said, “O My Dear Son! From where did you learn such exemplary words?” Hazrat Junaid-e-Baghdadi (radi Allaho anhu) said,”This is through the blessing of your esteem companionship.” [Masaalikus Saalikeen]
He was a great Aalim Mufti. He was ahead of all in wisdom and eloquence. From the beginning, right up to the end of his life, he was loved by all. Everyone was pleased with him as the leader. There is no person that can point even a finger at the Maqaam of Hazrat Junaid-e-Baghdadi (radi Allaho anhu). The only people who could not see the station of Hazrat Junaid-e-Baghdadi (radi Allaho anhu) were those who were blind in faith.? He was known as the voice of the people, but he always called himself Abdul Masha?ikh (the servant of the Masters). Many of the Ulama also called him Sultanul Muhaqiqeen. He had reached very high levels in Shariat and Tariqat. Many great Sheikhs followed his silsila. He was the greatest Sheikh of his era. He spent time in the khidmat of Hazrat Muhaasibi (radi Allaho anhu). Once someone asked Hazrat Sirri Saqti (radi Allaho anhu) if the Mureed can be more famous than the Peer and Hazrat Sirri Saqti (radi Allaho anhu) said, “Yes, it is possible. The perfect example is right before you. I am the Peer of Junaid-e-Baghdadi, but he is more exalted than me.”
Hazrat Junaid-e-Baghdadi (radi Allaho anhu) passed from this world, on a Friday, the 27th of Rajab, 297 or 298 Hijri. His Dargah (Mazaar) is in Shaunizia, which is in Baghdad Shareef.