If You Missed it Earlier

Check out this aritcle to find out where did signage begin. Historians speculate that the earliest signs were drawings etched on cave walls of tribal artisans to attract business. So for example, someone making bows or utensils could've created a visual cue - a sign - on their cave to draw customers, so historians believe.
http://www.artipot.com/articles/1748778/a-brief-history-of-the-sign-industry.htm