This guide is meant to help any player interested in the camp conversion mechanic, especially those who aren't familiar with it.
First off, here are a collection of convertible camps that I know of, and the factions they pertain to:
Pahlava/Saka: Nisaya, Bukharak, Chach, Oyrta and Shahr
Sauromatae/KB: Paniardis, Skythiapolis and soon to be(I believe), the territory directly north of the Caucasus. Not sure if that will be added to the Pahlava/Saka convertible list, I'm guessing it won't be.
Swebozes/Lugiones/Boii: Leufana, Luppae, Himbroburgz and Hleifpos
Nabatu: Rekem, Tadmur.
Numidians: Kirtan, Siga and Thugga.
If anyone knows anymore, then feel free to chyme in, but these are all convertible. As you can see, convertible camps are faction specific, so don't expect to convert German camps if you're the Numidians.
Secondly, why would you even want to convert camps? Or even want to play a nomadic faction which can transition to a settled faction? Why not just skip the work and play as a settled faction? Well, there are all sorts of benefits to camp conversion, including reforms tied to them, increased income in a settlement to settlement basis, more buildable structures and the potential for the construction of eastcols(only some factions get those) which will often greatly broaden your unit roster. More importantly, however, is that Nomadic factions which can convert camps and transition to settled factions have the potential to build much larger empires on average than other factions do, as the AI cannot convert camps(lamentably so). As the Romans or Carthaginians, Kirtan, Siga and Thugga will be camps forever, with incomes which can be useful, but never as large as they will be for the Numidians, once they convert these settlements and build a highway which stretches all across the northern reaches of Africa, from Lixus to Thugga(or maybe further if you've attacked the other 2 African based factions). That's something you never get to experience as the Romans or any faction in the game--only you can build those highways. Many of us have no doubt looked lamentably at the disconnected roads in settled areas which border on nomadic ones. If you capture A-E, Chach, Oyrta, Shahr and Kushi as Baktria, it's hard not to notice where the roads of kushi and A-E abruptly end at camp areas and thus are significantly more difficult to navigate. As the Saka or Pahlava, you can build a highway leading from Kushi and Chach across most of central Asia, a very cool feeling indeed. The governmental reforms of factions which transition from nomadic to settled are also extremely fun to install and vary quite a bit from faction to faction. Generally, as well, these reforms are excellent for building and maintaining large empires, which in some ways makes these nomadic factions which transition to settled almost more sophisticated in government than many of the Northern European tribes. Confederations drop authority points, but Satrapies and Royal satrapies do not, and are excellent forms of government which can be installed in MANY places(I was surprised that I could construct Satrapies at Rome, Arretium, Epidamnos and other areas as the Numidians, for example). Of course, this is not to say that Nomadic factions are better or more fun to play than Northern factions which don't have that level of freedom with direct governmental control(by design, because some are confederations). but only that building a larger empire is a bit easier as a transitioned faction which emulates Persian(Pahlava/Saka), Greek(nabatu) or other cultural government types.
As far as I know, the Swebozes and Lugiones can convert camps, but their only reforms are time based, and do not fully transition to a settled people unlike some of the other factions. The Sauromatae get better at governing cities in their reforms, but I wouldn't say that they truly become settled, and their reforms aren't as sophisticated in nature as the Saka or Pahlava. The KB are already a settled faction, who just happens to have many nomadic ties, and can more easily convert steppe peoples to settled forms of life(so far as I know).
Well, if you've read this far you're probably interested in just how the hell you do convert camps. This is done by building sedentary farming buildings in the camps which are convertible. Higher tiers of nomadic herds and farming are mutually exclusive, but just having the elite herds building(most basic nomadic herds) will allow you to build up to large-scale farming, which will in turn unlock the conversion building. Remember! This only applies to nomadic factions! I remember back in the days of 2.01, I tried destroying all the herds in Asanka, Lugidunon, Kalisia, Scurgum and Waldawa, as I'd read on the forums that to convert camps to cities you needed to destroy herds and build farms...Well, turns out you can't build farms in those areas anyway and since the Boii can't build the herds building, I just ended up hurting my population growth there. If you conquer somewhere where farms can't be built, keep the herds buildings there for increased income and pop growth, as you can't rebuild it.
It isn't usually as simple as just building the farms step by step though. Typically, these farms slowly lower nomadic cultures over time, up to a certain percentage, at which point the next tier of farm building should be unlocked. Slowly progress through the farm buildings until you reach the large farms, and after that is built you will be able to construct the 12 turn 6000 minai camp conversion structure, which permanently converts a camp to a settlement. For some factions, just converting a few camps will trigger a reform(for example, the Numidians), and most of the reforms for these nomadic factions which can transition to settled involve camp conversion. It usually takes a whole lot of turns to become a settled faction (somewhere in the vicinity of 200 turns for the Numidians and Saka), but trust me, they are very well worth it and will add a whole layer of depth to a campaign you might even be slightly bored with(it REALLY spiced up my Numidian campaign). I highly recommend playing as one of these transitional factions if you haven't, as their reforms are very rewarding. Most of these reforms involve a culture switch(or several), but at least one of these do not change culture(eg. Numidians), but the nomadic farms typically lower nomadism in a settlement until conversion is possible.
EDIT: You can generally tell whether a camp has the mixed resource by the province's relatively geography. Compare the amount of farmland, greenery and water in the environs of Thugga to that of Garama or Tuat, those places are much drier and more suited to a nomadic way of life, as well as not having significant enough numbers in population to become settlements(another big thing). You can see Cimbrodunon, Luppae and Leufana all have a bit of farmland near them, contrast this again with the Baltic areas which are heavily forested with but few visible farmland on the map, as well as not having significant enough populations to become settlements at this point in history.
If I think of anything else to add, I will, or if someone else would like to chyme in, feel free! I hope this guide has been helpful!