"They're finding their way here in this country and a lot of them went West into the hills and South into the hills and that's where the folks were playing bluegrass," he said.
"Somehow or another, the bluegrass and the Celtic kind of amalgamated in certain fashions but still had a clean, dividing line," Knode said.
"They've been influenced by one another," he said.
Vervan began teaching Irish sessions at Appalachian Bluegrass about a year ago.
He said he was a loyal customer long before he began leading Irish sessions and teaching classic violin.
"I was a loyal fan of the store and Emory," said Vervan, who lives in western Maryland.
So confident was Vervan in Appalachian Bluegrass' ability to provide the best product, he would order strings and equipment and have it shipped overseas while he was working as a musician in Germany and Ireland.
Though he is more well known at the store for his classic violin classes, he really enjoys teaching the Irish sessions that prepare beginners for the more experienced sessions that typically take place in a bar or pub.
"We play a variety of instrumental Irish music and we play slowly so that people have a chance to learn and also so people get a chance to experience what it's like to play a session," Vervan said.
Knode said the music taught by Thurston and Vervan is not only a lesson in Irish culture, but also in history.
"The musical tunes, the songs that Andy's playing on his guitar and his Celtic bands, go back generations," Knode said.
"The same tune played in the same way for years and years and years and years," he said.
"I call it a musical time machine. You can truly travel back in time and hear how music was played 200 years ago if you want, and it hasn't changed," Knode said.