The era emphasizes lattice-based models of ferromagnetism, domain dynamics, and high-frequency permeability, linking statistical mechanics with magnetic materials research. Researchers integrate spin-based theories with crystallography and dynamic responses to build a continuum from fundamental theory to device-oriented materials, paving the way for ferrite-based radio-frequency components and microwave magnetism. Historical significance: This period bridges microscopic spin interactions and macroscopic magnetization with practical observations of domain structures, dispersion, and resonance. By establishing a coherent framework across static and dynamic regimes, it anchors the evolution of ferromagnetic materials science and initiates a trajectory toward modern high-frequency magnetic materials research.