Amn has the good fortune to have abundant natural resources; some would say Amn is the richest land on the continent. This has worked in Amn's favor for generations, because even if they were conquered, the new masters would be gentle, looking to gain wealth from the land, rather than to put it to the torch.
Amn has been a center of trade and commerce for as long as anyone can remember. Oral traditions handed down from father to son tend to support the theory that Amn has been a trade center for at least 800 years. Unfortunately, written records are difficult to find and often incomplete. It would seem the typical Amnish citizen was too busy trying to fill their coffers to write down events of the day.
Amn has always been more interested in the present and the future than the past, and this makes an accurate history difficult. The best records, the business papers of the oldest trading companies, are jealously guarded. The fear of revealing "trade secrets" is stronger than the call of history, so the average citizen knows very little about Amn's past.
It appears that the Amn of 100 years ago was very much like the Calimshan of today. Each major city was basically an independent entity, banding together for defense when necessary, and fighting for control of territory and profitable trade routes the rest of the time. A particularly brutal trade war began 24 years ago, with each city exacting prohibitive tariffs on goods imported from the others. The trade war escalated, and city troops began to raid caravans sponsored by other cities. In a matter of months commerce was brought to a halt, a number of cities were under siege, and war threatened to engulf the entire region.
Into the breach stepped a young merchant named Thayze Selemchant. Thayze was smart, charismatic, and very well connected (the Selemchant trading house was one of the oldest and richest in Athkatla.) He secretly contacted representatives of the five other richest merchant houses in Amn, and started to plan.
The first part of the plan involved the careful sprinkling of rumors about outside threats. One involved a pirate invasion from the Nelanther, another was about a massing of orcs just on the other side of the Cloud Peaks. Thayze even started a rumor about an elf army in the Forest of Tethir, ready to pounce on a divided Amn. None of the rumors were true, but they began to turn people's thoughts toward unity, not war.
Thayze knew that if he and the other members of his council were to take control of Amn, they would need broad-based popular support. Tensions between cities and merchant houses were still high, so to get that support, Selemchant and the others agreed to drop their family names and never use them again.
When news of a "Council of Six" spread throughout the land, many people accepted their rule. A group that would unite Amn under one rule, governing for the benefit of all instead of one city or trading company over another, was indeed a welcome change. The Council raised an army (at great personal expense) to quell the few pockets of resistance that remained, and have been in total control of Amn for the past 22 years.