Learn Hardcore Malay: Di buku asas sejarah itu, ada banyak jenis peta. - In that basic history book, there are many types of maps.

Malay is flexible with word order, but fronting the location (di buku asas sejarah itu) is very natural and common when you want to set the scene:

Di buku asas sejarah itu, ada banyak jenis peta.
Literally: In that basic history book, there are many types of maps.

If you say:

Ada banyak jenis peta di buku asas sejarah itu.

this is also grammatical. The difference is slight in emphasis:

Fronted di buku asas sejarah itu: Emphasis on where (in that book, there are many types of maps).
Final di buku asas sejarah itu: Emphasis more on what exists (there are many types of maps, and they are in that book).

What exactly does di mean here, and how is it different from dalam?

Both di and dalam can be translated as in in English, but they’re used differently.

di is a general preposition for at / in / on (a location).
dalam has more of an inside / within feeling.

In many contexts with books, both are possible:

Di buku asas sejarah itu, ada banyak jenis peta.
Dalam buku asas sejarah itu, ada banyak jenis peta.

Both are acceptable. Dalam can sound a bit more like inside the book, while di is more neutral. In everyday speech and writing, di buku and dalam buku are both common; here, di does not sound wrong or informal.

How should I understand the phrase buku asas sejarah? Which word modifies which?

Malay noun phrases are usually head noun + modifiers (the opposite of English).

buku = book (head noun)
asas = basic, fundamental (adjective)
sejarah = history (noun used as a modifier here)

So buku asas sejarah is literally:

buku (book) + asas (basic) + sejarah (history)
= a basic book of history / basic history book.

English flips the order to: basic history book.
In Malay, adjectives (asas) and modifying nouns (sejarah) come after the head noun (buku).

Could we say buku sejarah asas instead of buku asas sejarah?

Not naturally, no. Buku asas sejarah is the usual, natural order.

You can think of the structure as:

buku [asas sejarah]
→ asas sejarah = basic history, and that whole phrase modifies buku.

If you say buku sejarah asas, it sounds odd or unclear, like book of history-basic rather than basic history book. So stick with buku asas sejarah.

What is the function of itu in buku asas sejarah itu?

Itu is a demonstrative meaning that / the (distal, not close by). Here it:

Points to a specific book both speaker and listener know about.
Often corresponds to that in English, or sometimes to a definite the.

So:

buku asas sejarah itu ≈ that basic history book / the basic history book (we’ve mentioned).

Without itu:

buku asas sejarah = a basic history book / basic history books (more general, not specific).

Why is there a comma after itu? Is it required?

The comma in:

Di buku asas sejarah itu, ada banyak jenis peta.

marks a pause between the location phrase and the main clause. It’s stylistically helpful but not strictly required. Many native speakers would still write it without the comma:

Di buku asas sejarah itu ada banyak jenis peta.

Both are acceptable; the version with the comma is a bit clearer to read.

What does ada mean in this sentence, and can it be omitted?

Here ada is the existential verb there is / there are:

ada banyak jenis peta = there are many types of maps.

In this structure ([location], ada [thing]), ada is normally used and generally not omitted. You would not usually say:

✗ Di buku asas sejarah itu, banyak jenis peta.

That sounds incomplete. You need ada to express existence: there is/are.

How is banyak used here? Does Malay need a plural ending for peta?

Banyak means many / much. It shows that the noun following it is plural or multiple in a natural sense:

banyak jenis peta = many types of maps.

Malay does not usually mark plural with an ending like -s. Number is shown by:

context,
numerals (tiga peta = three maps), or
quantifiers like banyak (many), beberapa (several), sedikit (a few), etc.

So peta alone can mean map or maps depending on context. With banyak jenis, it’s clearly maps.

What exactly does jenis add to the meaning of banyak jenis peta?

Jenis means type / kind / category.

banyak peta = many maps (just number of maps)
banyak jenis peta = many types of maps (variety; different kinds of maps)

So banyak jenis peta emphasises variety, not just quantity. It suggests physical, political, historical maps, etc., not just many copies of the same map.

Why isn’t there a word like yang in buku asas sejarah itu, ada banyak jenis peta?

Yang in Malay is mainly used to:

introduce relative clauses, or
turn adjectives into noun phrases.

This sentence doesn’t contain a relative clause; it’s a simple existential structure:

[Location] + ada + [noun phrase]

So:

Di buku asas sejarah itu, ada banyak jenis peta.

does not need yang anywhere. If you added yang here, you’d create a different structure and likely make it ungrammatical or at least strange.

Could I say this sentence in another natural way with the same meaning?

Yes, a few natural variants include:

Dalam buku asas sejarah itu, ada banyak jenis peta.
(Using dalam instead of di; still natural.)
Buku asas sejarah itu mempunyai banyak jenis peta.
Here mempunyai = has / possesses.
This shifts from a there are structure to a [subject] has [object] structure:
- Literally: That basic history book has many types of maps.
Banyak jenis peta terdapat dalam buku asas sejarah itu.
Terdapat is another verb meaning there is/are; can be found.
This version front-loads banyak jenis peta (many types of maps).