This is not necessarily true.
Romans, in the early Republic, were largely farmers. Yet, they were able to best the Greeks, who were as near to professional warriors as existed in the ancient world. And they were certainly able to overcome the Cisalpine Gauls.
And who did the warrior people tend to despoil? The settled groups, thatâs who.
On the other hand, (and Iâm telling this mainly because I like the story) the Persian King Cyrus (I think it was Cyrus) was tired of having his empire raided by Scythians, so he gathered an enormous army and set out into the Eurasian steppes to chastise them. As he did, however, the Scythians kept withdrawing deeper and deeper into the steppes, raiding his flanks now and then as the spirit moved them to do.
Ultimately, Cyrus sent a message to the Scythian king, challenging him to stand and fight. The Scythian response was something like this: âWe have no cities or crops to defend, but if you find the graves of our ancestors and disturb them, then you will know whether we will fight.â
Cyrus turned his army around and returned to Persia.