Since there are relatively few simple verbs in Persian for which one has to learn conjugation (more on this later), and since there are very few exceptions in Persian verb conjugation, it is an easy part of Persian grammar. The past simple tense, however, is even easier than the rest.
Like the English past simple tense, it states a thing that happened in the past.
In Persian, each verb has two different stems and all forms of the verbs are produced using one of the two stems; present stem and past stem. The past simple, of course, uses the past stem, and is made this way:
Past stem of the verb + one of the six past simple endings depending on the subject of the verb
Look at the conjugation of the verb "رفتن" (to go) in the past simple tense below to learn the six endings.
[you (pl.)] went
And here are some examples:
من به خانه رفتم.
انشتین به آمریکا رفت.
I went home.
Einstein went to America.
The third person singular form does not need an ending and is the same with the past stem of the verb. As you see, the infinitive of the verb is produced by adding "ن َ " to the past stem. Some more Persian verbs are listed below:
Here is another example of conjugation of a verb in the past simple tense:
[you (pl.)] were
The stress of a past simple verb is on the last syllable of its stem. In the infinitive form, the stress is on the last syllable of the whole word. (The infinitive is actually a noun and in nouns, the stress is always on the last syllable.)
دیروز علی مُرد.
مینا خوشحال شد.
موتور سعید خراب شد.
خندید و گفت «نه!»
[I] was tired.
The children slept.
Ali died yesterday.
You (pl.) laughed.
Mina became happy.
Saeed's motorcycle broke down. (literally: became ruined)
[He/She] laughed and said "No!"
A very important thing to note is that since the verb endings show their subjects, many Persian sentences do not contain subjects as separate nouns or pronouns (Like the first and last examples above).
As you saw in the examples, verbs always come at the end of sentences, except in very special cases (like the last example.)
A list of the most common Persian verbs with their past and present stems is available here in the grammar supplements section.