1700-900 BCE: Vedas are composed (Samhitas)

1700-1500 BCE: Rig Veda composed. Oldest known Sanskrit text. 1028 poems structured around 10 mandalas (2-9 probably predating 1 and 10) 

1200-900 BCE: The Aryans compose 3 other vedas – Yajurveda (further sub divided into Shukla- white- and Krishna - Black), Samaveda, Atharvaveda

The Indians settled around the 5 rivers of Punjab "hears" the Rig Veda. Vedas (Sankrit for Knowledge) are first of a set of epics that are seen by men of wisdom (Rishis who are manthra drashta, Rishi is from root Dris, meaning to see) - these are Apaurusheya (not of men). Idea being that the rishis got Vedas directly from a non human source (e.g. God). 

The Vedas constitute "Shruti" set of early Indian literature - Shruti is “that which has been heard” and is canonical, consisting of revelation and unquestionable truth, and is considered eternal having been "seen" by gifted priests directly from god. 

Simplistically, the 4 Vedas contain hymns, methodology of ritual, mode of singing hymns, charms for everyday purpose etc

Rig Veda : consists of hymns of praise to the various Vedic gods (Indra, Agni, Soma, Varuna ) primarily, but also some ritual detailing (eg. horse sacrifice)

Sample hymn to Agni (Lord of Fire, core to any sacrifice to accept oblations from humans ) ; Surprisingly in the below hymn, Agni is called "guard of law eternal" which is typically associated with god Varuna

Whatever blessing, Agni, thou wilt grant unto thy worshipper,

That, Angiras, is indeed thy truth.

To thee, dispeller of the night, O Agni, day by day with prayer

Bringing thee reverence, we come

Ruler of sacrifices, guard of Law eternal, radiant One,

Increasing in thine own abode.

Be to us easy of approach, even as a father to his son:

Agni, be with us for our wealth.

Yajur veda : consists of methodologies for rituals and sacrifices, which mantra to sing for which Yajna (ritualistic sacrifice) ; Krishna Yajur Veda (older of the two) is a mix of prose and poems. Shukla Yajurveda, like all other vedas are fully metrical (composed in poetic metrics). These include practical aspects of preparing for yajna (sacrifice) like preparing ground for fire, kindling of fire, layers of bricks for altar, placing of fire in fire pan etc. 

Mantra for the Soma Sacrifice (Metric, in poem)

May I the waters wet (thee) for life,
For length of days, for glory.
O plant, protect him.
Axe, hurt him not.
Obedient to the gods I shear these.
With success may I reach further days.
Let the waters, the mothers, purify us,
With ghee let those that purify our ghee purify us,
Let them bear from us all pollution,
Forth from these waters do I come bright, in purity.
Thou art the body of Soma, guard my body.

Sacrificial ritual sample from Krishna Yajur Veda in Prose form

He who desires food should offer a brown (beast) to Soma; food is connected with Soma; verily he has recourse to Soma with his own share; he bestows food on him; verily he becomes an eater of food. It is brown; that is the colour of food; (verily it serves) for prosperity.

He who is seized by evil should offer (a beast) with a spot on the forehead and horns bent forward to Indra, the overcomer of enemies ; the enemy is the evil; verily he has recourse to Indra, the overcomer of enemies with his own share, and he drives away from him the enemy, the evil. 

Sama veda : methodology of singing the hymns contained primarily in Rig Veda with very little that is not in RV. 

Atharva veda : consisting primarily of hymns & charms for every day life (winning lover, removing disease, long life, charms against evil etc). 

Sample : Charm to win love of a woman

1. As the creeper embraces the tree on all sides, thus do thou embrace me, so that thou, woman, shalt love me, so that thou shalt not be averse to me!

2. As the eagle when he flies forth presses his wings against the earth, thus do I fasten down thy mind, so that thou, woman, shalt love me, so that thou shalt not be averse to me.

3. As the sun day by day goes about this heaven and earth, thus do I go about thy mind, so that thou, woman, shalt love me, so that thou shalt not be: averse to me.

Special note on horse

The vedic people had huge centrality for horses - on one side it was their main animal of movement. They moved about since the horse eats grass from roots (unlike say cow) and hence need vast expanses. On other side, it was also sacrificial beast. Very detailed instructions on how to sacrifice, how to build sacrificial altars, how to put agni in the altar, how to offer oblations etc are part of vedas.

The horse sacrifice was important and probably the largest, most well attended ritual among the people mandating details on how it needs to be conducted (RV, 1.162)

The robe they spread upon the Horse to clothe him, the upper covering and the golden trappings,

The halters which restrain the Steed, the heel-ropes,-all these, as grateful to the Gods, they offer.

The four-and-thirty ribs of the. Swift Charger, kin to the Gods, the slayer's hatchet pierces.

Cut ye with skill, so that the parts be flawless, and piece by piece declaring them dissect them.

They who observing that the Horse is ready call out and say, the smell is good; remove it;

And, craving meat, await the distribution, -may their approving help promote labour.

May this Steed bring us all-sustaining riches, wealth in good kine,good horses, manly offspring.

Freedom from sin may Aditi vouchsafe us: the Steed with our oblations gain us lordship!