I received several answers in the comments and was really impressed by the knowledge, and the quality of the glasses of the contributors. All together, you've almost identified everything, except for a few guys in the background.
Here you are the answer. I am going to give the detail of the sets used, and the manufacturers of course. As you will see, I summoned almost every tribe of the ancient world :)
Let's begin with the easy part, those who you all recognized.
1. The sets you all recognized
1.1. Caesar set H040 - Ancient Germans
1.3. Hät set 8069 - Dacians
1.4. Hät minisets 6005 - Picts, and 6008 - Visigoths (the lonely man on the left)
1.5. Hät miniset 6007 - Franks
1.6. Strelets set M035 - Ancient Germans
1.7. Strelets set M004 - Vikings (I have painted other vikings, but they were too well equipped to look like ancient Germans)
1.8. Esci set 225 - Barbarian Warriors (yes, it is possible to use descent poses from this improbable set - I remember a time when it was the only available set representing ancient Germans, I then used every pose. The kneeling archer is a conversion from this set)
So far, all these manufacturers had been identified by most of you. The following have been named by Paul (from Paul's Bods) only.
2. The sets identified by Paul
2.1. Miniart set 72013 - Germanic Warriors
2.2. Orion set 72028 - Slavic Warriors (ok, this one is not in the right warband, let's say he is a neighbour visiting his friends)
2.3. Coates & Shine set 8133 - Gothic Army (ok, it is almost a Hät reference)
The last ones had not been identified - they were completely lost in the background !
3. The figures lost in the background
3.1. Revell sets 02553 Celts (Gauls) and 02551 - Anglo-Saxons (The "Gaul" is on the left - nothing to do with a Celt, but it can be a descent Frank)
3.2. Emhar set 7206 Saxon Warriors
And last, a family picture - the mix is the best way to represent that sort of warband.
This picture is not blurry, will you find them all ? :)