Is efrog the original brythonic name for York? I thought the word 'York' itself was directly from the old brythonic name for the area ╮(╯▽╰)╭
"York" comes from the Norse name Jorvik. But the city pre-dates the Viking period by centuries; it was called Eboracum by the Romans, which presumably is a Latinisation from a Celtic word similar to Efrog.
The usual etymology is from Common Brythonic *Iburakon, meaning "Place of Yew Trees". The Welsh looks like it could've either come directly from that or from the Latinized name, I'm not sure which.
York/Jorvik is ultimately from the Latin name too, incidentally. Latin Eburacum → Old English Eoforwic, which anglicized the name by using Old English words that sounded similar to the Latin name, Eofor = boar, -wic = town. The -f- there was pronounced [v]. The final -um in the Latin had probably already been lost in the local dialect of Vulgar Latin by the time the Anglo-Saxons arrived. Then when the Norse invaded the area, they adapted Eoforwic as Jorvik, replacing -wic with their own -vik meaning the same thing, and changing the diphthong /e͡o/ which Old Norse lacked to /jo/, as well as dropping the /v/ sound, if it hadn't already been dropped by the English-speaking locals. Then, of course, Jorvik was gradually worn down to York.
Finally, a town I think I've heard of. Do people only learn Welsh if they're going to Wales? Is that why specific place names come so early in the lessons?
Well, this course is based on courses to teach Welsh to people in Wales. For that, place names would definitely be useful. It was probably carried over in an attempt to bring some Welsh geography into the course. (I don't know how much these show up later in the course--I just started.)
Yes, I had forgotten that Welsh had almost died out. I'm glad it's making a comeback.
There aren't many other places in the world with significant numbers of Welsh speakers, so yes primarily people are going to learn Welsh to use in Wales.
Is this meant as New York, USA, or is there a place called New York in Wales?