A common misconception is that speaking in tongues did not exist until the Azusa Street revival in 1901
Quoting from the Article “10 THINGS CHRISTIANS SHOULD KNOW ABOUT THE PENTECOSTAL CHURCH”
It’s largely believed that the Azusa Street revival in 1906 marked the birth of modern Pentecostalism. At the revival, evangelist William J. Seymour preached about baptism of the Holy Spirit and the gift of speaking in tongues.
However, others have said that speaking in tongues may have started as early as 1896 and 1901, when the Apostolic Faith movement began.
Widely considered the first person to speak in tongues, in 1901, Bible school student Agnes Ozman spoke in tongues in Kansas. Evangelist Charles Parham called it “Bible evidence” for baptism in the Holy Spirit.
However actual History teaches us differently
These people through the annals of history may not have used the tag “PENTECOSTAL”, but they were in practice like modern Pentecostals.
Quoting now from the Article by Joe Townsley The History of Tongues
Montanism was a prophetic movement that broke out in Phrigia in Roman Asia Minor (Turkey) around 172AD. It made tongues-speaking a central part of their worship experience. Montanists followed Montanus of Phrygis, who said he was the chosen instrument of the Spirit to prepare the church for the second coming. He taught a strict asceticism, which soon developed into legalism. It was condemned by bishops in Asia and elsewhere. A residual sect persisted in Phrygia for some centuries before it disappeared. 
By the middle of the fourth century, the practice seems to have diminished in the West,  although Vincent Ferrer and Francis Xavier were missionaries who described their miraculous ability to communicate with various groups as glossolalia,  and other examples exist.  In addition many believe that in the Eastern church tongues-speaking continued to be practiced in Greek Orthodox monasteries throughout the Middle Ages. 
At the end of seventeenth century, widespread tongues-speaking occurred for a little over a decade in southern France among a group of persecuted Huguenots. Similarly, in the 1730s an occurrence of tongues-speaking happened among a group fo Catholic pietists, called the Jansenists. 
Then in the 1830s until the end of the century a revival of tongues-speaking occurred in England during the ministry of Edward Irving. After reports that tongues-speaking had occurred in the west of Scotland in the spring of 1830, Irving himself shortly after reported such expressions in his Regent Square Church. Until the end of the century his followers (Irvingites) made tongues-speaking central to their church life. 
The example of the Huguenots and Irvingites then led to similar occurrences in Mother Anne Lee’s Shaker movement in England and America, and among the Mormons in America where Joseph Smith’s followers in New York, Missouri, and Utah began practicing tongues-speaking.  Not long after, in the 1850s, a tongues-speaking movement began in Russia that continued throughout the century. 
Similarly, beginning around 1860 on the Southern tip of India, through the influence of Plymouth Brethren theology  and the leadership of the Indian J.C. Aroolappen a revival of tongues-speaking and prophecy was reported.