It is one of the "family books" (mandalas 2–7), the oldest core of the Rigveda, which were composed in early vedic period(1500-1000 BCE).
[1] The Rigveda Anukramani attributes all hymns in this book to Vāmadeva Gautama (son of Maharishi Gautama), except for hymns 43 and 44, attributed to Purumīḍha Sauhotra and Ajamīḍha Sauhotra.
tuvâṃ hí agne sádam ít samanyávo 4.2 (298) [Agni.]
tuvám mahâṁ indara túbhya * ha kṣâ 4.18 (314) [Indra and Others.]
â yātu índro ávasa úpa na 4.22 (318) [Indra.]
yán na índro jujuṣé yác ca váṣṭi 4.23 (319) [Indra.]
gárbhe nú sánn ánu eṣām avedam 4.28 (324) [Indra-Soma.]
tuvâ yujâ táva tát soma sakhyá 4.29 (325) [Indra.]
â na stutá úpa vâjebhir ūtî 4.30 (326) [Indra.]
táṃ vāṃ ráthaṃ vayám adyâ huvema 4.45 (341) [Asvins.]
eṣá syá bhānúr úd iyarti yujyáte 4.46 (342) [ Vayu.
yás tastámbha sáhasā ví jmó ántān 4.51 (347) [ Dawn.]
ábhūd deváḥ savitâ vándiyo nú na 4.55 (351) [ Visvedevas.]