A mining operation in a remote hidden area, that ended up finding an artifact level treasure, the chaos shard. It is an unlikely coincidence, but you also need to consider the larger situation. The goblins have very good reason to want their forward bases hidden, places like the valley are ideal for their purposes. Which means they specifically seek out of the way, underdeveloped areas that they can build settlements in. They are also a faction with hundreds of thousands of members, which in turn means they could have many bases like this one. Also, don't assume anything happening to Richter is truly random. A lot of things are more easily explained with the lords or the gods or a third faction stacking the deck in his favor. Could even be another exile - they all want to get out but they probably also all want to be the one to break the lock, imagine the status and power crushing the Land would bring. Sabotaging their rivals would be right up their alley.