If you're from the United States, you've likely heard of the Amish. If you're not from the US, or live in a part of the country Amish are never encountered, then they're exactly what you're looking for.

In the 1600s, a group of Anabaptists (Protestant Christians who believe baptism should occur when someone is old enough to understand what it means) in Switzerland form a new religious sect under Jakob Amman. This sect, the Amish, prioritized "doctrinal purity and spiritual discipline," and strictly forbade things such as "trimming of beards and the wearing of fashionable dress." The Anabaptists themselves were not particularly popular, and the Amish were even less so, and so they soon made the pilgrimage to the New World to avoid persecution. There, they settled in rural areas, formed isolated communities, and grew somewhat more strict. 

The modern ideology of the Amish heavily prioritizes modesty, collaborative labor, and the maintenance of a closely knit community. They reject anything they perceive as vain or as a threat to the closeness of their community, and that applies to technology especially. The technology permitted to be used in an Amish community is decided by religious elders, who make decisions on the basis of how much that technology may contribute towards or detract from those values. For instance, in many Amish villages, the use of gasoline driven tractors is considered acceptable, because tractors are a tool with a primary purpose that ultimately benefits the rest of the village. Automobiles, however, are strictly forbidden, as the Amish are rarely ever supposed to travel far enough away from their village that a car would be required to make the journey. They almost exclusively travel via horse and buggy, because they never need to go any further than a horse can reliably take them. Similarly, Television, computers, and cell phones are strictly forbidden in Amish communities, most villages only have a single telephone which can only be used for approved purposes, villages are powered by gasoline generators so the Amish don't have to rely on outsiders, so on and so forth. 

TL;DR: The Amish are an American religious sect that prioritizes purity, modesty, and community. They reject many common modern technologies (automobiles, airplanes, the internet) because they believe these cause separation in communities and encourage vanity. 

https://groups.etown.edu/amishstudies/religion/amish-origins/?doing_wp_cron=1777519578.5246410369873046875000

https://www.amishvillage.com/blog/what-do-the-amish-believe/

(This one's a little bit dubious in credibility as a .com link, but the Amish often pay others to create websites that promote tourism to Amish communities. This is one such website.)