Learn Hardcore Indonesian: Sejak itu, tetangga kami saling menyapa setiap pagi. - Since then, our neighbors greet each other every morning.

Indonesian nouns usually don’t show number. On its own, tetangga kami can mean either. Here, saling (“each other”) signals that the subject must be plural, so the natural reading is “our neighbors.”

To force singular:

seorang tetangga kami = one of our neighbors
tetangga kami itu = that neighbor of ours (previously mentioned)

To make plural explicit:

para tetangga kami (more formal)
tetangga-tetangga kami (reduplication; neutral in writing, can feel heavy in speech)

What does saling do here, and where does it go in the sentence?

Saling marks reciprocity: the participants do the action to each other. It normally precedes the verb: saling + verb (e.g., saling menyapa). Because it implies at least two participants, pairing it with a clearly singular subject is odd or ungrammatical. You wouldn’t say “dia saling menyapa.”

Can I use satu sama lain instead of saling?

Yes:

Tetangga kami saling menyapa.
Tetangga kami menyapa satu sama lain.

Both mean “greet each other.” Using both together—saling menyapa satu sama lain—is common in speech but is redundant in careful writing.

Is there a more idiomatic alternative to saling menyapa?

Yes, bertegur sapa means “to exchange greetings” and is inherently reciprocal:

Sejak itu, tetangga kami bertegur sapa setiap pagi. You can see or hear saling bertegur sapa, but the saling is not necessary.

Does this sentence include “us” as participants, or only the neighbors?

As written, the subject is tetangga kami (“our neighbors”), so it describes neighbors greeting one another (not necessarily including “us”). If you want “we and our neighbors greet each other,” say:

Kami dan para tetangga saling menyapa setiap pagi.
If including the listener: Kita dan para tetangga saling menyapa setiap pagi.

Why kami and not kita?

Both mean “we/our,” but:

kami excludes the listener (“we/our” not including you).
kita includes the listener (“we/our” including you).

So tetangga kami = “our neighbors” (not including the person you’re talking to). Tetangga kita would include them.

What’s the nuance of Sejak itu compared with Sesudah itu or Mulai saat itu?

Sejak itu = “since then” (starting at that time and continuing up to a later reference point, often now).
Mulai (saat) itu = “starting from that moment” (very similar to sejak itu).
Sesudah itu = “after that/then” (describes sequence, not ongoing continuity). “Sejak ini” isn’t used; for “from now on,” use mulai sekarang or mulai saat ini.

Is the comma after Sejak itu required? Can I move Sejak itu or setiap pagi?

The comma is standard after a fronted time phrase. You can move the time phrases:

Sejak itu, tetangga kami saling menyapa setiap pagi. (as given)
Tetangga kami saling menyapa setiap pagi sejak itu.
Setiap pagi, tetangga kami saling menyapa sejak itu. Fronting time phrases is common and natural in Indonesian.

What’s the base of menyapa, and why does it look like that?

The root is sapa (“to greet”). With the meN- prefix, initial s in the root drops and the prefix surfaces as meny-: meN- + sapa → menyapa. Similar patterns:

sapu → menyapu (“to sweep”)
susun → menyusun (“to arrange”)

Is menyapa transitive? Can I add a direct object with saling?

Menyapa is normally transitive:

Saya menyapa tetangga saya. (“I greet my neighbor.”) With saling, the participants act on each other, so you typically don’t add a separate object:
Kami saling menyapa. If you want an explicit object phrase, use satu sama lain:
Kami menyapa satu sama lain.

Are there alternatives to setiap pagi?

Yes:

tiap pagi (very common)
setiap pagi hari (slightly more formal/literary)
pagi-pagi (sekali) means “early in the morning,” not “every morning.” So don’t say “setiap pagi-pagi.”

Is para necessary to mark the plural in para tetangga kami?

No. Plural marking is optional in Indonesian; context (and here, saling) already implies plural. Para explicitly marks a group of people and is common in formal writing: para tetangga kami. In everyday speech, plain tetangga kami is usually enough.

Can I add sudah/telah to show a change since then?

For a habitual action with setiap pagi, you normally don’t add sudah/telah. If you want to emphasize the new state without the habitual adverbial, you can say:

Sejak itu, kami sudah saling menyapa. Keep setiap pagi for the routine; use sudah/telah to emphasize completion/onset when not describing a repeated schedule.

Is saling sapa acceptable?

In casual speech you’ll hear saling sapa or sapa-menyapa, but standard Indonesian prefers a fully-formed verb: saling menyapa or the idiom bertegur sapa. For clear, standard usage, stick with those.