[gleeaikin]

Given the harsh winters in the Highlands, and other lacks of worthy goods, especially in bad crop years, the wall was not doubt used to keep the norther tribes from attacking the more prosperous southern areas. Approximately the same reason we are building a wall to keep the less prosperous neighbors to the south from overrunning the USA. Are there any lessons to be learned from this history???

[BroJoeK]

"Are there any lessons to be learned from this history???"

A timeless lesson, goes back to Romulus & Remus:

"In response to Romulus' construction, Remus made continuous fun of the wall and his brother's city.
Remus was so bold as to jump over Romulus' wall jestingly.
In response to Remus' mockeries and for jumping over his wall, Romulus, angered by his brother's belittlement, killed him."

An undefended wall is easily breached.
A defended wall, not so much.

[ZULU]

It worked.