Quite a few villages, towns and cities have their name ending in -ingen: Sigmaringen, Singen, Villingen-Schwenningen (combo), Donaueschingen, Memmingen, Tübingen, Überlingen, Uhldingen. I could go on and on.
What is the origin and the meaning of this suffix?
From experience, I think this is prevalent in Baden-Württemberg. Could it be a Swabian thing?
The suffix "-ingen" describes the affilation to a leader or a person in general. So in Sigmaringen lived the relatives of Sigmar.
This is not a swabian thing, as you can find many town names with this suffix (even in Europe). It comes from the transmigration when regions were settled by germanics.
The origin of this suffix is old high german or germanic. It comes from "ing" or "jung" and means child.
Sources (in German):
-ingen (or -ing,-ung, -engo and others) denotes affiliation to a person, place or geographic landmark. It is common in names of persons and places in many European regions where Germanic languages had or have influence on local culture.
Some examples include:
Other places can be found in Sweden, Denmark, the Netherlands', Switzerland, northern Italy and other regions.
The accepted and most-voted answer refuses the regional aspect of the suffix -ingen. It had been used to name places wherever Germanic peoples settled including Scandinavia and Great Britain and generally refers to a person (see also Merovingian, Carolingian). Still, the OP is right in suggesting that it is much more prevalent in Southern Germany: Among the many possible ways to name places some have been more popular in certain regions and periods of time.
In particular, the ending -ingen is typical for the Alemannic colonization in the 6th and 7th century (Oltner Tagblatt) and also for the Bavarian settlement.
](https://i.stack.imgur.com/yU25d.png)
The visualization is taken from a site by Moritz Stefaner which shows the geographic distribution of different endings within Germany (results also accessible via a Stern online "article"). Some of the more notable:
-ach: Mostly in Frankish settlement areas in the Palatinate and Southern Hesse, but also in Saxony and Baden. Less frequently found in Bavaria and other parts of Southern Germany. Unusual in Northern Germany.
-au: Mostly in the Western part of the former GDR along a belt between Lübeck and Zwickau. This ending may either be Slavic (-ow, -ov,...) or Germanic. In the latter case the name indicates the presence of a meadow.
-bach: (indicating the presence of a creek) The distribution is similar to -ach but doesn't extend eastward into Thuringia and Saxony.
-berg: (indicating the presence of a mountain or hill) Places with this suffix can be found almost everywhere in Germany.
-bruch: (indicating that there had been a swamp) Mostly in old Saxon settlement areas in Westfalia and Lower Saxony.
-dorf: (village) Mostly in Eastern Germany. Settlements of this type were founded during the Ostsiedlung.
-feld: (field) Almost everywhere in Germany, but rare in most parts of Southern Germany.
-itz: Very frequent in Eastern Germany, but absent in Western Germany as the suffix is of Slavic origin.
I have heard that Swiss German attests to same phenomenon with the etymologically related GN ending -ikon (e.g., Dietlikon, Pfäffikon, Zollikon).
The suffix ingen is taken from the ancient Allemani language, and means “the people from.” The Allemani were an old Germanic tribe.
