Ancient beam transporters are highly advanced teleportation devices very similar to Asgard beaming technology. The beam transporter technology of the Ancients has only been encountered a few times, and so it is not known if it was developed before they ascended or afterwards.
The beam transporters of the Ancients can send a person or object from one location to another without the need for platforms, unlike Transportation rings and those on Atlantis. Operating in a manner very similar to Asgard transporters but with a considerably faster transport time, Ancient beam transporters are able to beam large amounts of matter through a Stargate. (SG1: "Avalon, Part 2", "The Quest, Part 2")
This form of transporter may have been developed after the fall of the Ancients using knowledge Merlin gained during ascension, since it was never seen on anything prior to Avalon. Otherwise it would have likely been in their final facility, before they gave up and allowed themselves to pass into extinction, ascension, and assisting various human civilizations in the Milky Way. Featured in outposts such as the one on Camelot. These devices were used to store Merlin's treasure in a buffer and beam it into a chamber if the proper tests were passed, and were also used in conjunction with another form of Ancient transporter technology to beam the contents of an entire mountain through a Stargate. (SG1: "Avalon, Part 2", "Camelot", "The Quest, Part 2")
A technology very similar to Ancient beam transporters was also used in conjunction with a variant Repository of knowledge to assemble what had been designed in its virtual buffer from its molecules up. (SG1: "The Quest, Part 2")