A mechanistic understanding of brain development requires a systematic survey of neural progenitor cell types, their lineage specification and maturation of postmitotic neurons. Cumulative evidences based on single-cell transcriptomic analysis have revealed the heterogeneity of cortical neural progenitors, their temporal patterning and the developmental trajectories of excitatory and inhibitory neurons in the developing neocortex. Nevertheless, the developmental hierarchy of the hypothalamus, which contains an astounding diversity of neurons that regulate endocrine, autonomic and behavioral functions, has not been well understood.