The Adventurer's Guild. No matter which country you went to, the one thing you would find in common would be the Adventurer's Guild. The guilds are neutral and are not under the control of any government.
However, Ainz convinced the E-Rantel guildmaster Pluton Ainzach to allow Ainz to incorporate the E-Rantel Adventurer's Guild into the Sorcerer's Kingdom.
To show his sincerity, Ainzach proceeded to explain in detail how the Adventurer's Guild works, and furthermore, he reveals to Ainz his secret meetings with the Magician's Guilds' guildmaster, Theo Lachesil. Since he thought that Ainz already knew about these meetings, it was better to simply be honest so that Ainz will trust him. It was also so that Ainz will allow him and his old friend, Theo Lachesil to become adventurers again, this time as true adventurers, going to explore the unknown.
Adventurers are separated into different classes; Copper, Iron, Silver, Gold, Platinum, Mythril, Orichalcum and Adamantite.
Adamantite Adventurers, the adventurers at the very top of the ladder, close to reaching the heroic level, are what all adventurers aspire to be, yet few will ever become one. Before Ainz took over E-Rantel, there were 3 Adamantite adventurer teams in the Kingdom, including Momon's Darkness. The Empire has the Silver Thread Birds, and the Eight Ripples. Although the Eight Ripples cannot be considered strong enough to be Admantite adventurers individually, because of their team work, we can call them an Adamantite level team. Even so, if we counted all of the known Adamantite adventurer teams, they number less than 10. And no country would have the good fortune of having more than 3 Admantite teams. Each Adamantite level adventurer would be worth a thousand troops.
Orichalcum Adventurers on the other hand, while still considered elites, are relatively more common. You can usually find 4-5 Orichalcum teams in every large city. Experienced Orichalcum adventurers can take on powerful monsters such as the gigant basilisk. Each Orichalcum adventurer was equivalent to about 700 troops.
Mithril Adventurers are the lowest tier of adventurers still considered as elite. In smaller cities without Adamantite or Orichalcum adventurers, the Mithril teams would be the most senior and authoritative within the guild. A team of Mithril adventurers can handle an elder lich, and Mithril adventurers are as strong as 300 troops.
Platinum, Gold, and Silver Adventurers form the intermediate tier of adventurers. The most any normal person could ever hope to achieve no matter how much hard work they put in would be around Gold level. Though not as respected as the top tier elite adventurers, these adventurers can still make a decent living. Thus many people train hard and end up working as an intermediate tier adventure. Of course, there are also a few promising young adventurers who are still gaining the experience and prestige needed to reach the elite tier of adventurers.
Finally, we have the Iron and Copper Adventurers. Though you can always see many Iron and Copper plates in the guild, the turnover rate is very high. Many young men and women come and apply to become an adventurer, after listening to tales and legends of the mighty Adamantite adventurers. However, most would quit after a short while, after realizing how difficult and dangerous being an adventurer really was, and that it wasn't anywhere near as glorious as they had once thought. Still, these beginners can be helpful in taking out weak creatures such as skeletons, or provide relatively cheap protection for people without a lot of money, leaving more important jobs for the higher tier adventurers.
The city of E-Rantel, having been an important trading hub at the border of three countries, as well as being in the vicinity of the dangerous Forest of Tob and Katze Plains, boasted a very large and robust Adventurer's Guild that could rival even the one in the Capital. Many aspiring adventurers come to E-Rantel from all over the country in hopes of catching the eye of an experienced elite adventurer so that he could study under him, while others come for the abundance of lucrative jobs. In total, E-Rantel boasted over 1,000 adventurer teams. If we exclude the Adamantite team "Darkness", E-Rantel was still home to 5 Orichalcum teams, 15 Mithril teams, 70 Platinum teams, 120 Gold teams, 250 Silver teams, and over 600 Iron and Copper teams.
Ainzach also explained the existence of workers. Workers were, for the most part, just like adventurers. However, because there are various restrictions put on Adventurers, like not being allowed to take tasks that are political in nature, or to cast healing spells on people who can not afford them, some people choose to leave the Adventurer's Guild and form their own teams, as well as their own contacts and clients. Because adventurers at the Adamantite level, are so rare and important, they are usually given quite a bit of leeway for their actions. As a result, there was no reason for an Adamantite ranked adventurer to become a worker. Thus the highest level of workers you would find would be Orichalcum-level workers. That said, there weren't any Iron or Copper level workers either, simply because they are too weak to work by themselves. Most of the workers were around the Gold and Platinum level.
Due to being at the border between the Kingdom, the Empire and the Theocracy, there E-Rantel was also the perfect place for workers to thrive. Workers were often hired to spy on another country, or otherwise operate in an area not under their own control. Because there are no official records of workers, there is no exact count on the number of workers active in E-Rantel. That said, around 200 worker teams (with 1 Orichalcum team, 4 Mithril teams, around 30 Platinum, 80 Gold, and the rest Silver) would be as good an estimate as any.
Unfortunately, soon after E-Rantel fell to the Sorcerer Kingdom, most of the adventurers fled to other cities. Others, thinking that the fall of the Re-Estize Kingdom was near, defected to the Baharuth Empire. Not even a third of the Adventurers are left in E-Rantel. But what hurts the most was that the quality of adventurers also dropped considerably. This was understandable, as the stronger adventurers also had an easier time moving, as they have the money, the contacts, and also the reputation to be easily accepted into another Adventurer's Guild. Of the original 5 Orichalcum and 15 Mithril teams, only a single Mithril team, lead by an adventurer by the name of Moknak was left. And all the worker teams seems to have gone in hiding.
This was not good news for Ainz, who wanted a strong Adventurer's Guild to show off to the rest of the world.