Door de mist zagen we geen verkeer.

Because Dutch often puts extra information first for emphasis or style. Here, Door de mist gives the reason or circumstance first.

In a normal main clause, Dutch keeps the finite verb in the second position. So when Door de mist is moved to the front, the verb zagen must come next:

• Door de mist zagen we geen verkeer.

A more neutral order would be:

• We zagen door de mist geen verkeer.

Both are possible, but the given sentence emphasizes the fog.

Door often means through, but in this sentence it is commonly understood as because of or due to.

So door de mist means:

• because of the fog
• due to the fog

Dutch uses door in this causal sense quite often:

• Door de regen bleven we thuis. = Because of the rain, we stayed home.

So although door can literally mean through, here it expresses the cause.

This is because of the Dutch verb-second rule in main clauses.

In a normal statement, the finite verb must be in the second position. If the sentence begins with the subject, you get:

• We zagen geen verkeer.

But if something else comes first, like Door de mist, then the verb must still stay second, and the subject moves after it:

• Door de mist zagen we geen verkeer.

This inversion is very common in Dutch.

Zagen is the past tense plural form of zien (to see).

Conjugation of zien in the past tense:

• ik zag = I saw
• jij zag = you saw
• hij/zij zag = he/she saw
• wij zagen = we saw
• jullie zagen = you saw
• zij zagen = they saw

So in this sentence:

• zagen we = we saw

It is an irregular verb, so you have to learn these forms separately.

Use geen to negate:

• a noun without an article
• an indefinite noun
• a general absence of something

Here, verkeer is an uncountable noun, so Dutch uses geen:

• geen verkeer = no traffic / not any traffic

You would not say niet verkeer here.

Compare:

• We zagen geen verkeer. = We saw no traffic.
• Het verkeer was niet druk. = The traffic was not busy.

So geen negates the noun, while niet usually negates adjectives, verbs, adverbs, or definite nouns.

Because verkeer here is used as an uncountable noun, like traffic in English.

Dutch often leaves out the article with uncountable or abstract nouns when speaking generally:

• We zagen geen verkeer. = We saw no traffic.
• Er is verkeer op de weg. = There is traffic on the road.

If you add geen, that already works as the determiner, so you do not also use een or het.

Because mist is a de-word in Dutch:

• de mist = the fog

Unfortunately, whether a noun takes de or het often has to be memorized. There are some patterns in Dutch, but many nouns simply need to be learned individually.

So:

• de mist
• door de mist

Grammatically, verkeer is usually treated as a singular uncountable noun, similar to English traffic.

So even though traffic consists of many vehicles, Dutch treats it as one mass noun:

• Het verkeer is druk. = The traffic is busy/heavy.
• We zagen geen verkeer. = We saw no traffic.

You do not normally use it as a countable plural meaning vehicles.

Grammatically, door de mist can sometimes look like through the fog, but in this sentence the most natural reading is because of the fog.

If you really wanted to say through the fog, Dutch would more often use wording that makes the spatial meaning clearer, depending on context.

So for learners, the safest interpretation here is:

• Door de mist = because of the fog

The structure is:

• Door de mist = adverbial phrase giving cause
• zagen = finite verb
• we = subject
• geen verkeer = direct object

So the pattern is:

• Adverbial + Verb + Subject + Object

This is a very common Dutch main-clause pattern whenever something other than the subject comes first.

Yes, that is possible, but it can be a little more ambiguous.

• We zagen geen verkeer door de mist could still mean because of the fog we saw no traffic
• but word order may make the relationship less immediately clear

Starting with Door de mist makes the cause more prominent and often sounds more natural if that is the main point:

• Door de mist zagen we geen verkeer.

So both can work, but the original sentence is clearer and more idiomatic in many contexts.