I think this question would benefit from being a little more specific as ‘African tribal people’ includes a vast area with multiple cultures and kingdoms, most of which came into contact with Europeans in different ways at different times.

I can tell you a little about contact in West Africa as I did my PhD on a closely related topic.

The short answer is that it’s likely many coastal West Africans would have been aware of Europeans in the 1700s.

Let’s unpack this a little. It is hard to exactly determine how much the ‘average’ West African would have been aware of Europeans, and how many actually came into day-to-day contact. The sources we have available are mostly accounts by Europeans who visited the coast, plus West African artistic representations, and the remains Europeans left behind them there (i.e. the archaeology). My answer mostly focuses on the archaeology.

The Portuguese were the first Europeans to visit the West African coastline in the mid to late 15th century.

We know this from the depictions of them in art from the kingdom of Benin (which confusingly, is located in modern-day Nigeria). These are the Benin Bronzes, large flat bronze squares depicting religious, social and political events and scenes commissioned by the Oba (I.e. king) of Benin. They now reside in the British Museum. Some of these bronzes depict the Portuguese - easy to distinguish by their features, clothing (including very distinctive hats/helmets) and muskets. Of course, these were made by master craftspeople for the Oba to display, so it’s not quite the same as understanding the ‘average’ person’s awareness.

Another solid piece of evidence are the many forts built on the West African coasts by Europeans. These were built as somewhere to house goods, to trade, as fortifications. One of the most well known ones is El Mina on the coast of Ghana, close to the capital, Accra. This was built by the Portuguese on 1482 but changed hands several times, captured by the Dutch in the 1700s and eventually coming into the possession of the English in the 1800s.

El Mina is unfortunately well-known because it was a slave fort. Captured West Africans were held here in the 17-1800s before being taken through the ‘door of no return’ and onto slave ships to a life of horror.

There was also a thriving trade in goods in the 1700s between Europe and West Africa, with Europeans trading cowrie shells (in particular) for cloth and precious metals. We know this from shipping logs and manifests, and from caches of cowries found on the coast.

So - we know Europeans had a fairly strong coastal presence in the 1700s.

There is evidence to suggest that Europeans were known of further inland during this time period, or at least the slave trade was. Excavations by Anquandah in Northern Ghana in the 1980s uncovered small red clay figurines of people, some of whom were depicted as wearing chains or had their mouths bound and covered. These figurines were provisionally dated to the 17-18th century (some other animal and human figures were dated as early as the 12th century AD in excavations from the 2000s, but that’s another story).

This evidence indicates that many West Africans living or working along the coast would have been aware of Europeans, starting in the 15th century AD. With this awareness unfortunately heightened by the trans-Atlantic slave trade and the part of several European empires in that.

I hope that’s helpful and I can dig out some more concrete sources if you’re interested. Hopefully someone else can answer for other parts of the continent.

Edit to add: it may also be worth looking up Mansa Musa, the king of the Empire of Mali in West Africa in the 14th century. The king travelled extensively, including going on pilgrimage to Mecca - written records of this survive. Granted he is earlier than the time period you asked about but it’s pretty interesting context for later interactions and contact.