Lethian was the founder of Lethian's Crossing and architect of its success. Although Lethian was a mediocre merchant, she was a great leader. The war in the Northern Kingdoms cost her a very lucrative trade route up north, but she managed to earn trade stewardships from Kyros, and for a short time she had a monopoly on grain, salt, and tin in the Tiers. However, the next year, Lethian was stripped of her trade rights. Suddenly she had a large staff but no goods to trade and no means to pay anyone. Stubborn as a mule, she knew that if she just kept at it, eventually things would turn around for her. Rather than seek goods out, she focused on bringing them to her.
So she decided to concentrate on making an existing local settlement into the center of commerce for the Tiers and she did just that. Choosing a town nestled up to the Oldwalls seemed crazy, but Lethian's instincts proved correct. As a master of knots (a veritable Archon of the Rope), Lethian meticulously planned an extensive system of pulleys and mobile bridges based on dry dock mechanisms she observed in coastal cities. They would help her create an overland (or rather, over-Oldwall) route that would greatly reduce the travel time between the Bastard Tier and Haven. The hardest part was getting the initial climbing team to brave the Oldwalls and set the first ties, but pay a man enough rings...
The rope bridges let people cross the Oldwalls. With them, it didn't matter what trade rights she had, as her town would be at a crossroads to the Northern Tiers - an unbeatable location. It wasn't long after that it was renamed in her honor - and with the bridges over the Oldwalls, this was the only place to go if traders wanted to take weeks off of their trip. Eventually, she hired the Bronze Brotherhood to act as local guards. They were big enough and had enough commerce to warrant the protection.