Yajur Veda is one of the four Vedas, considered as the oldest scriptures of Hinduism.
It is estimated to have been composed around 1200 to 1000 BCE, roughly contemporaneous with Sama Veda and Atharva Veda.
The Samhita portion of Yajur Veda consists of hymns (some taken from the Rig veda) that are to be articulated by priests when performing sacrificial rituals. There are two versions of Yajur Veda – (1) Krishna (or Black) Yajur Veda (2) Shukla (or White) Yajur Veda. The primary difference between the two is that in the Krishna version, the commentary on the material is part of the text, while the commentary in the Shukla version appears in the appendix at the end of what is regarded as the “pure” version of the Samhita. The Shukla Yajur Veda also contains some additional material.
Krishna Yajur Veda contains Taittiriya Brahmana, whilst the Shukla Yajur Veda includes the Shatapatha Brahmana.
The Krishna Yajur Veda also contains the Taittiriya Aranyaka. The final book of the Shatapatha Brahmana is regarded as either an Aranyaka (the Brihad Aranyaka) or an Upanishad (the Brihad Aranyaka Upanishad).
The Taittiriya Upanishad, the Katha Upanishad and the Shvetashvatara Upanishad are part of the Krishna Yajur Veda. The Brihad Aranyaka Upanishad and the Isha Upanishad are included in the Shukla Yajur Veda.