At the beginning of the First Era, the Kingdom of Argonia was conquered by Empress Alessia. The trade between the Alessian Empire and Argonia prospered and in the Thogrof Hills a well defendable trading post was built. Many trade goods were brought towards Blacklight, from where they were transported by horse even farther. But because of the extension of the trading route via the port of Tear and the border expansion in the year 1E 1029, the Argonian trading post continously decreased in importance and was eventually almost forgotten.
More than one thousand years later, a group of Fythung smugglers discovered the expanded natural rock caves and started to use them as a resting place and hideout. When the Thrassian Plague broke out and more than half of Tamriel's inhabitants were killed. The smugglers also had to deal with their casualties.
The few survivors secured their loot with numerous traps and left to seek a cure. They knew, that when they came back, that they would be able to identify the traps' positions by certain noises to deactivate them.
The smugglers never returned, and their traps remained active. Many archaeologists do not think that the caves would be worth it to search. For many years, all survivors have told of is of horrible fluttering creatures, terrible traps, and not one of them was willing to return to the caves, and risk his or her life again.