Fox News reports that archeologists have unearthed a walled town dating back to 4,200-4,700 B.C. "[T]he walls, which are 6 feet high and 4 ½ feet thick, are believed to be the earliest and most massive fortifications from Europe's prehistory." The settlement consisted of two-story houses and was near rock-salt deposits. "The two-story houses, as well as the copper needles and pottery found in graves at the site, suggest a community of wealthy people whose likely work was the once-lucrative production of salt." The article reports the archeologist, Vasil Nikolov, as saying the walls were to protect the salt. They were also to protect the people.
Note the walls. I recently finished a book on prehistoric warfare that discussed how common (incessant may be a better word) banditry, raids, and small-scale warfare was (and is) among pre-literate peoples. Even with the wide-spread warfare and crime rates we experience today, we actually live in a much safer world than our ancestors did.