Trial by Blood and Fire is a forbidden area continuously sealed by ancient wind attribute restriction. The restriction has a five-day period of weakness every sixty years. During this period of opening, if several Core Formation experts simultaneously used force against the restriction, they could create a temporary opening and let a certain amount of people inside. There lies another restriction which restricts cultivators of Foundation Establishment and above from entering. However, cultivators of Qi Condensation stage were not obstructed in the least. After years of plundering of resources inside the forbidden area, there was a massacre of disciples from the seven sects of State of Yue by demon beasts and disciples of other sects due to scarce resources, resulting in survival rate of less than one third. This led to the forbidden area being called 'Trial by Blood and Fire' by these sect's disciples.
This forbidden area contains ingredients that are required to make the Foundation Establishment Pills which were necessary for Qi Condensation cultivators to breakthrough their bottleneck and enter Foundation Establishment stage.