Страна происхождения указана в таможенной декларации.

Because страна is the main noun, so it appears in the nominative singular: страна.

The word происхождения is in the genitive singular because Russian often uses the pattern:

• noun + genitive noun

to express something like X of Y.

So:

• страна происхождения = country of origin
• literally: country of origin/of coming from

This is a standard Russian noun phrase, especially in formal or official language.

Происхождения is genitive singular.

Its dictionary form is происхождение. Here it changes to происхождения because it depends on страна and specifies what kind of country it is:

• страна происхождения = country of origin

This is similar to other Russian expressions like:

• центр города = city center
• номер паспорта = passport number
• дата рождения = date of birth

So the genitive here is not showing possession in the narrow English sense; it is just a very common way to connect nouns.

Because указана agrees with страна, which is:

• feminine
• singular

So the form must also be feminine singular.

Here are the matching short-form patterns:

• masculine: указан
• feminine: указана
• neuter: указано
• plural: указаны

Examples:

• Адрес указан.
• Страна указана.
• Место указано.
• Данные указаны.

Since страна is feminine, указана is the correct form.

Указана is the short-form passive participle of указать.

In sentences like this, it works very much like a predicate and is often translated as:

• is indicated
• is stated
• is specified
• is listed

So Страна происхождения указана... means something like:

• The country of origin is indicated/stated/listed...

This short-form participle is very common in official, written, and bureaucratic Russian.

In Russian, the verb to be is usually omitted in the present tense.

So where English says:

• The country of origin is indicated...

Russian simply says:

• Страна происхождения указана...

That is normal.

Compare:

• Он врач. = He is a doctor.
• Документ готов. = The document is ready.
• Страна происхождения указана. = The country of origin is indicated.

If you wanted the past or future, forms of быть would appear:

• Страна происхождения была указана... = was indicated
• Страна происхождения будет указана... = will be indicated

It is the prepositional case after в, because here в means in in the sense of location.

So:

• в декларации = in the declaration
• в таможенной декларации = in the customs declaration

The noun декларация becomes:

• nominative: декларация
• prepositional: декларации

And the adjective таможенная changes to match it:

• nominative feminine singular: таможенная
• prepositional feminine singular: таможенной

Because adjectives must agree with the nouns they describe in:

• gender
• number
• case

Here the noun is декларации, which is:

• feminine
• singular
• prepositional

So the adjective must also be feminine singular prepositional:

• таможенной

You can think of the phrase as:

• в таможенной декларации
• in the customs declaration

where both words are in the same case.

Yes, very much so.

It is the standard formal way to say country of origin, especially in contexts like:

• customs forms
• shipping documents
• product labels
• import/export paperwork

A learner should treat страна происхождения as a common set phrase.

Yes, but the meaning and style shift a little.

• Страна происхождения указана в таможенной декларации. = The country of origin is indicated/listed in the customs declaration.

This sounds like a statement about a completed fact or about what the document contains.

• Страна происхождения указывается в таможенной декларации. = The country of origin is indicated/is to be indicated in the customs declaration.

This can sound more like a general rule, instruction, or standard procedure.

So:

• указана = the information is there
• указывается = this is what is indicated / should be indicated as a rule

Yes. Russian word order is flexible, although the neutral order here is perfectly natural:

• Страна происхождения указана в таможенной декларации.

Other orders are possible for emphasis, for example:

• В таможенной декларации указана страна происхождения.

This version puts more focus on where the information is found: in the customs declaration.

So the sentence can be rearranged, but the original word order is standard and natural in formal writing.

Because that would mean something different.

• страна происхождения = country of origin
• происхождение страны = the origin of the country

The second phrase sounds like you are talking about how a country itself came into being historically. That is not the intended meaning here.

So for customs or product documentation, страна происхождения is the correct phrase.

It is definitely formal/official in tone.

Words and structures like:

• страна происхождения
• указана
• таможенная декларация

are very typical of bureaucratic, legal, administrative, or technical language.

In everyday speech, a person might phrase the idea more simply depending on context, but on forms, labels, and official documents, this sentence sounds completely normal.

The standard stress is:

• странá происхождéния указáна в тамóженной деклара́ции

Word by word:

• странá
• происхождéния
• указáна
• тамóженной
• деклара́ции

Stress is important in Russian pronunciation, so it is worth learning these forms together with the sentence.