Assalaamu alaykum. I have three questions:
1. Can you pay zakah in the form of goods, like food and cloths etc.? And if not, then see my following question, please.
2. Then, in the article of zakah, it is said that every Prophet as well as their people gave zakah, but if that was in the form of money, then how could Noah's nation and Noah pay zakah with money given that money was not used until between 5000 BC to 3000 BC because, since we agree we all come from the ark, then in no way could Noah's ark have been between that time. Also metal was not used till 9000 BC. However, if zakah can be paid with goods, then question two is answered because then his people would have given zakah in the forms of goods. And also how did Ishmael's people pay zakah, if in the form of money, given that they had just arrived in the desert?
3: Verse 25:20 does not mean the markets wear necessarily using money, does it? It could have been done by bartering, is that correct? Again, in Noah's time, there was no money, and certainly not in metal because that metal came much later. May Allaah reward you.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

First of all, it should be noted that in principle zakaah should be paid from the same kind on which it is due; if the zakaah is due on crops, for example, then zakaah must be given out from the crops; if the zakaah is due on animals, then it must be given out from the animals, and if the zakaah is due on money, then it must be given from the money. This is the principle.

If we presume that in those ancient ages people did not have any money, then your question has no meaning, because there was no money – according to what you mentioned – to say that the zakaah was obligatory on money or that money would be given as zakaah for other things.

As regards giving the zakaah as value, that is to say if a person must pay the zakaah on crops, for example, is he permitted to pay the zakaah as money [instead of giving it from the crops] or as other things that are equivalent to the value on which the zakaah is obligatory? Then this is a matter of difference of opinion among the scholars. The Hanafi School permitted it, while the majority of the scholars forbade it.

The preponderant view on this matter is the view chosen by Shaykh Ibn Taymiyyah which is that giving the monetary value in zakaah is sufficient if there is a benefit for the poor in doing that.

As for what you mentioned about the previous nations and how they paid their zakaah, then this is a matter which only Allah knows. Allah legislated laws that are suitable for every nation, as Allah says (what means): {To each of you We prescribed a law and a method.} [Quran 5:48]

A person who has a sound mind preoccupies himself with what benefits him in his worldly life and the Hereafter, especially if there is no way to know the reality of what he is inquiring about.

Allah knows best.