Tuberculosis (TB) remains a significant global health issue, with Mycobacterium tuberculosis (MTB) being the causative agent. The evolution of MTB from less virulent mycobacteria has been a subject of intense study, aiming to understand how it became a dominant pathogen. This review highlights new insights into the genus-level evolution of mycobacteria, focusing on key genomic events that enabled the emergence and dominance of MTB. It also reviews the various lineages of MTB, their host preferences, and geographic distribution. The evolution of MTB is discussed, including the role of horizontal gene transfer (HGT) and specific mechanisms like distributive conjugal transfer. The 25th anniversary of the MTB genome sequence is marked, emphasizing its impact on comparative genomics and postgenomic studies. The review covers the evolution of MTB at the genus level, the emergence of MTB from environmental mycobacteria, and the specific evolutionary events that led to the development of MTB as a human pathogen. It also discusses the phylogenetic relationships of MTB and its close relatives, the *Mycobacterium canettii* clade, and the evolutionary significance of genomic regions like the fumarate reductase locus. The article concludes by exploring the evolution of MTB lineages, including the deletion of the *cobE* gene locus and the loss of regions of difference (RDs), which have contributed to the intracellular parasitic lifestyle and adaptation to mammalian hosts.Tuberculosis (TB) remains a significant global health issue, with Mycobacterium tuberculosis (MTB) being the causative agent. The evolution of MTB from less virulent mycobacteria has been a subject of intense study, aiming to understand how it became a dominant pathogen. This review highlights new insights into the genus-level evolution of mycobacteria, focusing on key genomic events that enabled the emergence and dominance of MTB. It also reviews the various lineages of MTB, their host preferences, and geographic distribution. The evolution of MTB is discussed, including the role of horizontal gene transfer (HGT) and specific mechanisms like distributive conjugal transfer. The 25th anniversary of the MTB genome sequence is marked, emphasizing its impact on comparative genomics and postgenomic studies. The review covers the evolution of MTB at the genus level, the emergence of MTB from environmental mycobacteria, and the specific evolutionary events that led to the development of MTB as a human pathogen. It also discusses the phylogenetic relationships of MTB and its close relatives, the *Mycobacterium canettii* clade, and the evolutionary significance of genomic regions like the fumarate reductase locus. The article concludes by exploring the evolution of MTB lineages, including the deletion of the *cobE* gene locus and the loss of regions of difference (RDs), which have contributed to the intracellular parasitic lifestyle and adaptation to mammalian hosts.