Why no "the"?
They are the names of towns in the area.
Answer: Because the writer of the statement did not want to imply that the list of names was complete and exhaustive.
"the names of the towns in the area" implies "the names of all the towns in the area".
The writer simply wanted to say "the names of some towns in the area".
"the" with a plural implies "all". For example, suppose there are
exactly three bottles on a table, all of them broken. You can say
The bottles on the table are broken or
All the bottles on the table are broken.
Both mean the same thing. The word "all" adds nothing, logically
speaking, in such cases. So the omission of "the" with a
countable plural noun generally indicates that we are speaking of fewer
than all the entities under consideration.
CJ