We have so little information about the area before the arrival of Arab traders mainly because the people living there did not leave many written records, relied heavily on oral tradition, and lived in environments that were hard for outsiders to reach and document.

Before Arab traders

Before Arab traders began moving regularly through the trans-Saharan region, most local societies passed down history, laws, and stories by word of mouth rather than in writing. Oral tradition can preserve culture, but it leaves little permanent evidence for later historians once storytellers die or communities are disrupted.

Lack of written records

Many groups in the region did not develop, use, or widely spread writing systems in a way that produced archives like chronicles, tax lists, or official correspondence. Without such documents, modern knowledge of their politics, everyday life, and belief systems is much thinner than for societies that kept written records.

Geography and access

The Sahara and surrounding areas are vast, harsh, and difficult to cross, which limited how often outsiders visited, mapped, or described them in detail. Fewer visitors meant fewer outside written accounts to supplement local oral histories, so much of that early past remains archaeologically and historically obscure.

When Arab traders arrived

With the arrival of Arab traders, long-distance trade routes intensified and connected the region more closely to literate centers in North Africa and the wider Islamic world. These traders and associated scholars produced more written descriptions of routes, peoples, and kingdoms, which is why information suddenly becomes more abundant in the historical record after their arrival.

TL;DR: There is little information from before Arab traders because earlier societies relied on spoken tradition, left few written records, and lived in remote, hard-to-reach regions, so only once literate Arab traders and connected scholars took interest do detailed written sources begin to appear.

Information gathered from public forums or data available on the internet and portrayed here.