I mean, it can be hard to measure "development", but come on. We don't even have proper sources to know where the capital cities were at the time in the area. You're just making a wild guess here. It's really unlikely that "much of west africa" was more populated or more urbanized than western europe.
Just because we want to rehabilitate Africa in modern science doesn't mean that we are allowed to make wild claims like this.
Or maybe you're confused with the christian and muslim kingdoms of Abyssinia, which is the only place (aside from northern Africa) that we know had comparable urban and societal landscapes to Europe at the time.
Good catch (and even better in the context of my previous post. got the hypocrite of me. but maybe we shall move it to another thread?)
it has 2 parts again.
First, look at the dates I intentionally pointed out. I was talking about 1066 and 867 respectively, dates in which Central and partially also Western Europe was not yet what we all see as medieval Europe, with many busy cities etc.
1066 is only a beggining of this, right before Europe started to get this shape. In mid 11th century the urban centers are yet few - in France and Germany still mainly limited to old Roman cities, most of them having barely very few thousand inhabitants, in Central Europe still practically non-existant. The foundations of feudal Europe have just been laid in the country with first castles, some of which would later turn into castles or cities, others would remain small. All that big urbanization is yet to start right away in the late 11th and 12th century (and later). 867 is obviously much worse in this respect, as all of the advanced civilization is limited to old Roman cities or very few newly found capitals such as Moravian Veligrad.
On the other hand, (2nd part) in the Western Sahel, the local civilization has just passed its peak. We don't have many written sources, but archaeology is more than clear that in 4 relatively large regions, (Mema, Hodh/Hawd and around Inland Niger delta + Kawkaw AKA later Songhay) there were dense nets of urban and sub-urban populations with with centers/capitals like Jenne-Jeno, Kumbi Saleh, Awdaghost and Gao with 10-15 or 15-20 thousand inhabitants, surrounded by clustered net of dozens smaller urban artisan/craft centers with 2-5 thousand people and dense net of smaller urban or rural settlements.
We don't know names for most of these, only their modern ones with the medium-size cities being for instance Hambarketelo (near Jenne), Kolima, Akumbu or Toladie in Mema etc., but they existed. In area approximately as large as Northern France to Rhine and (including) SW Germany
Some of those places declined and/or relocated before and during the period in question, but the peak of this urbanized culture(s) is, according to archaeology, roughly between 800-1100, with foundations in the 4th-5th centuries and declining in the warmer 12th century which expanded Sahara some 150-200 kilometers southwards.
The late 13th and 14th century saw relative revival of this civilization, with the core of economic and political life moved southwards to Manding and along the Niger, but from archaeological perspective the density and level of urbanization has never since reached the leves of 9th-11th centuries.
EDIT: Conclusion
I consider this relatively on par with mid 11th century France and Lowlands and most certainly more urbanized civilization than contemporary eastern half of Germany, Bohemia, Poland or Hungary...and even 9th century non-Mediterranean France.
EDIT2: which means, no, I haven't confused them with Nubia or Abyssinia. Although Nubia - according to archaeology - certainly wasn't far behind Egypt. But I don't consider it Sub-Saharan Africa.
(+ some additions, minor corrections and I had to make some grammar and spelling corrections, writing from a phone)