[Vocabulary] overland caravan routes that connected the swelling towns of the agricultural era

[nininaz]

"In many ways, these 21st-century malls are nothing new. In fact, they follow a long tradition of commercial expansion
that began with the development of the first long-distance trade networks and markets.
These markets were temporary at first, but became
more permanent with rise of cities in Middle East about five thousands years ago. They grew alongside the rivers, harbors, and overland caravan routes that connected the swelling towns of the agricultural era."
what does the swelling mean?! and what does whole bold text mean?!
Is the 3rd definition correct?!
http://www.oxfordlearnersdictionaries.com/definition/english/swell_1?q=swell

 

[Roman55]

I am not a teacher.

'Overland caravan routes' were the routes followed by groups of traders with their camels crossing desert lands from point A to point B.
'…that connected the swelling towns of the agricultural era.' These towns (see below), that existed during this agricultural period represent the points connected by the caravans.

The third definition is correct. It means 'the towns that were growing in size'.

There are a few mistakes in the third sentence. '…more permanent with the rise of cities in the Middle East about five thousand[STRIKE]s[/STRIKE] years ago.'