Dulu kami sering berkumpul di rumah nenek setiap akhir pekan.

Dulu gives a past-time background, like back then, in the old days, or used to depending on context.

In this sentence, dulu tells you that the whole situation happened in the past:

• Dulu kami sering berkumpul... = Back then, we often gathered...

It does not work exactly like an English past-tense verb ending. Instead, Indonesian often uses time words like dulu, kemarin, tadi, or tahun lalu to show when something happened.

Because Indonesian verbs do not change for tense the way English verbs do.

So:

• berkumpul can mean gather, gathered, are gathering, or will gather
• the time is understood from context or from time markers like dulu

In this sentence:

• dulu = past
• sering = often / used to do something regularly

So even though berkumpul itself does not change, the full sentence clearly refers to a repeated action in the past.

This is a very common and important question.

Indonesian has two words for we:

• kami = we, but not including the listener
• kita = we, including the listener

So kami is used here because the speaker is talking about their group in the past, and the listener is not part of that group.

• Dulu kami sering berkumpul... = Back then, we often got together...
  The person being spoken to is outside that we.

If the listener were included, Indonesian would use kita.

Sering means often.

It usually comes before the verb:

• kami sering berkumpul = we often gathered

That placement is very natural in Indonesian. It works a lot like English often before the main verb.

Other examples:

• Saya sering pergi ke sana. = I often go there.
• Mereka sering makan bersama. = They often eat together.

So in your sentence:

• kami = we
• sering = often
• berkumpul = gather / get together

Berkumpul means to gather, to get together, or to assemble.

It comes from the root kumpul, which relates to being together or collected. The prefix ber- often makes an intransitive verb, meaning the subject does the action without a direct object.

So:

• kumpul can appear in casual speech
• berkumpul is the more standard full form

Examples:

• Kami berkumpul di taman. = We gathered in the park.
• Keluarga itu berkumpul saat Lebaran. = That family gathers at Eid.

In your sentence, berkumpul suggests meeting together socially, probably as a family.

Because di marks a location, while ke marks movement toward a destination.

• di rumah nenek = at grandmother’s house
• ke rumah nenek = to grandmother’s house

Your sentence focuses on where the gathering happened, not on the movement there.

So:

• Kami sering berkumpul di rumah nenek. = We often gathered at grandmother’s house.
• Kami sering pergi ke rumah nenek. = We often went to grandmother’s house.

That is the key difference:

• di = location
• ke = direction / destination

In Indonesian, possession is often shown simply by putting the possessor after the noun.

So:

• rumah nenek = grandmother’s house
• literally: house grandmother

This is completely normal Indonesian word order.

More examples:

• buku saya = my book
• mobil ayah = father’s car
• nama guru itu = that teacher’s name

So rumah nenek does not need an apostrophe or a word like of.

Not by itself.

Nenek just means grandmother or sometimes grandma. In context, because the subject is kami, a listener will usually understand that this is probably our grandmother’s house, but the sentence itself does not explicitly say our.

If you wanted to be more explicit, you could say:

• rumah nenek kami = our grandmother’s house

But in many real situations, rumah nenek is enough because the relationship is obvious from context.

Because Indonesian does not normally use articles like English a, an, and the.

So:

• rumah can mean a house, the house, or just house
• the exact meaning depends on context

In di rumah nenek, the context makes it clear that this means at grandmother’s house, and English naturally uses grandmother’s house without needing to force an article there.

This is one of the biggest differences from English: Indonesian often leaves definiteness unstated unless it really needs to be clarified.

Setiap akhir pekan means every weekend.

Breakdown:

• setiap = every / each
• akhir pekan = weekend

So:

• setiap akhir pekan = every weekend

A useful point: Indonesian usually does not need to pluralize the noun after setiap.

So even though English says every weekend, Indonesian simply says:

• setiap akhir pekan not
• setiap akhir-akhir pekan

Other examples:

• setiap hari = every day
• setiap minggu = every week
• setiap tahun = every year

Yes, akhir pekan is a standard and common way to say weekend.

• akhir = end
• pekan = week

So it literally means end of the week.

In conversation, some speakers may also use other expressions depending on region or style, but akhir pekan is widely understood and very natural in standard Indonesian.

Yes. Indonesian word order is fairly flexible, especially with time expressions.

Your sentence:

• Dulu kami sering berkumpul di rumah nenek setiap akhir pekan.

A natural alternative would be:

• Dulu setiap akhir pekan kami sering berkumpul di rumah nenek.

Both are understandable. The original version sounds smooth and natural, and placing setiap akhir pekan at the end works well because it adds the frequency/time frame after the main action.

Indonesian often moves time expressions around for emphasis or style.

The sentence suggests a habitual past action, and in natural English it is often best understood as something like:

• Back then, we often gathered at Grandma’s house every weekend.

That said, English may feel slightly repetitive with both often and every weekend together. Indonesian allows this combination more comfortably.

The idea is that this was a regular pattern in the past. Depending on context, English might translate it more naturally as:

• We used to gather at Grandma’s house every weekend.

So sering emphasizes repeated frequency, while setiap akhir pekan gives the regular time pattern.

Usually not in natural English.

While dulu can refer to the past, formerly sounds too formal or too specific in many contexts. In this sentence, better choices are:

• back then
• in the past
• used to
• sometimes just a simple past translation

So a natural translation would be:

• Back then, we often gathered at Grandma’s house every weekend.
• We used to gather at Grandma’s house every weekend.

Those sound much more natural than using formerly.

It is quite natural and neutral. It works well in normal spoken or written Indonesian.

A few notes:

• dulu is very common in everyday speech
• kami sering berkumpul is standard and natural
• akhir pekan is neutral and standard

So this sentence does not sound unusually formal, but it is also not slangy. It is a good model for standard Indonesian.