The eighth Mandala of the Rigveda has 103 hymns. Other than the "family books" (Mandalas 2–7, dated as an old part of the RV) and RV 1 and RV 10 (dated as the latest portion of hymns composed shortly before redaction of the Rigveda into shakhas), Mandala 8 cannot straightforwardly be dated as a whole relative to the other books, and its hymns may include both ancient and late specimens. Most hymns in this book are attributed to the kāṇva family. The hymns 8.49 to 8.59 are the apocryphal vālakhilya, the majority of them are devoted to Indra; these are accepted as a recent portion, properly already post-Rigvedic.
Chitra is King, and only kinglings are the rest, who dwell beside Sarasvati. He, like Parjanya with his rain, hath spread himself with thousand, yea, with myriad gifts.
RV 8.21.18: (quoted in Lal, B. B. (2005). Can the Vedic people be identified archaeologically?–An approach. IT, 31, 173-194.)
Split apart the enclosure of the cow and the horse like a stronghold for your comrades.
RV 8.32.5
Quoted in Danino, M. (2019). Demilitarizing the Rigveda: a scrutiny of Vedic horses, chariots and warfare., STUDIES IN HUMANITIES AND SOCIAL SCIENCES Journal of the Inter-University Centre for Humanities and Social Sciences VOL. XXVI, NUMBER 1, SUMMER 2019
Break open for us the thousands of the Cow and the Horse.
RV 8.34.14, Sri Aurobindo's translation
quoted in M Danino in History of ancient India / editors, Dilip K. Chakrabarti and Makkhan Lal. v. 3. The texts, political history and administration, till c. 200 BC. I.2. The Horse and the Aryan Debate
Variant translations:
Break open for us cattle and horses in their thousands.
quoted in Danino, M. (2019). Demilitarizing the Rigveda: a scrutiny of Vedic horses, chariots and warfare., STUDIES IN HUMANITIES AND SOCIAL SCIENCES Journal of the Inter-University Centre for Humanities and Social Sciences VOL. XXVI, NUMBER 1, SUMMER 2019
We drank soma, we became immortal; we went to the light, we found the gods; how could now affect us distress, O Immortal One, how man’s malevolence?
Hymn 8.48.3, quoted from Kazanas, N. (2015). Vedic and IndoEuropean studies. Aditya Prakashan. chapter Shamans, Religion, Soma and the
We must, I think, suppose that the Avesta and RV. viii. are younger than RV. ii.-vii.; or else that the poets of viii. were geographically nearer to the Avestan people, and so took from them certain words...
Hopkins, Edward W. Prāgāthikāni. pp. 23-92 in JAOS (Journal of the American Oriental Society), Vol. 17. (pp 80-81). Quoted in Talageri, S. G. (2010). The Rigveda and the Avesta. New Delhi: Aditya Prakashan.
There is a peculiarity about these points of resemblance which is not so commonly known: It is the eighth Mandala which bears the most striking similarity to the Avesta. There and there only (and of course partly in the related first Mandala) do some common words like uṣṭra and the strophic structure called pragātha occur. … Further research in this direction is sure to be fruitful.
J.C. Tavadia, Indo-Iranian Studies: I, Visva Bharati, Santiniketan, 1950. Also quoted in Talageri, S. (2000). The Rigveda: A historical analysis. New Delhi: Aditya Prakashan.