Dengang boede jeg i byen.

This is because Danish follows the V2 rule in main clauses: the finite verb usually comes in the second position.

In Dengang boede jeg i byen:

• Dengang = first position
• boede = second position
• jeg = subject, which comes after the verb here

So the structure is:

Dengang + boede + jeg + i byen

If the sentence started with the subject instead, you would get:

Jeg boede i byen dengang.

That is also correct, but the emphasis is slightly different.

Dengang is a time expression meaning something like at that time, back then, or in those days.

It places the whole sentence in a past time frame. It is not the verb tense itself that gives the idea of back then; that comes from dengang.

So in this sentence, dengang tells you that the speaker is talking about an earlier period of life.

The verb boede is the past tense of bo (to live, in the sense of residing somewhere).

The present tense is:

• bor = live / am living

The past tense is:

• boede = lived / was living

So:

• Jeg bor i byen = I live in the city
• Jeg boede i byen = I lived in the city

The ending -ede is a very common past tense ending in Danish verbs.

Byen is the definite form of by:

• by = town / city
• byen = the town / the city

Danish often adds the definite article to the end of the noun instead of using a separate word like English the.

So:

• i byen = in the city / in town

You would use i den by only in more specific situations, for example when you are contrasting one city with another:

• i den by, jeg kom fra = in the city I came from

In your sentence, i byen is the natural form.

It can mean either, depending on context.

In many cases, by is a general word for an urban place, so English might translate it as:

• town
• city

Likewise, i byen can mean:

• in town
• in the city

The exact English choice depends on context, but the Danish itself is perfectly normal.

Because in Danish, the definite article is usually attached to the noun as an ending.

So:

• en by = a town / a city
• byen = the town / the city

This is one of the big differences from English. Instead of saying a separate word like the city, Danish often says by-en.

Yes, absolutely.

Both are correct:

• Dengang boede jeg i byen
• Jeg boede i byen dengang

The difference is mostly about focus:

• Dengang boede jeg i byen puts back then first, so the time frame is emphasized.
• Jeg boede i byen dengang starts more neutrally with I.

This kind of movement is common in Danish, but the V2 rule still applies in main clauses.

This is a very common question.

In many cases:

• dengang = back then / at that time
• da = when

So:

• Dengang boede jeg i byen = Back then, I lived in the city
• Da jeg boede i byen, ... = When I lived in the city, ...

Notice the difference:

• dengang can stand on its own as a time adverb
• da often introduces a clause

For example:

• Dengang var alt anderledes = Back then everything was different
• Da jeg boede i byen, tog jeg bussen hver dag = When I lived in the city, I took the bus every day

Bo usually means to live / reside somewhere, and it can be used for both longer-term and shorter-term living arrangements, depending on context.

For example:

• Jeg bor i København = I live in Copenhagen
• Jeg boede hos min moster i tre måneder = I lived with my aunt for three months

So in your sentence, boede simply tells us where the speaker lived at that time. It does not by itself say whether the situation was permanent.

A careful approximation is:

DENG-gang BOH-the yai ee BY-en

A few notes:

• dengang has stress on the first syllable
• boede is often pronounced roughly like BOH-the in standard speech
• jeg is often pronounced closer to yai than to a fully clear yeg
• byen can sound roughly like BY-en, though in natural speech it may be smoother and more compressed

As always with Danish, the spelling is often more transparent than the actual pronunciation, so listening to native audio helps a lot.

Yes, in some contexts i byen can mean something like in town or even be part of expressions about going out into town.

For example:

• Vi tager i byen = We are going into town / going out

But in Dengang boede jeg i byen, the meaning is clearly about where someone lived, so here i byen means in town / in the city as a place of residence.

Yes, it is a complete and natural Danish sentence.

It has:

• a time expression: Dengang
• a finite verb: boede
• a subject: jeg
• a place expression: i byen

So it is grammatically complete and sounds perfectly normal as a standalone sentence.