When people talk about international SEO, they often focus on expanding into new markets, countries, and languages to increase their market share.

However, there can also be great gains in optimising for another language within your own country. But even then, it’s not always a straightforward process, as there are regional differences and dialects to take into account.

Modern international SEO is also far more strategic than it once was, meaning targeting multilingual audiences within a single country is no longer simply a case of translating content or implementing hreflang tags correctly.

International SEO has evolved

When hreflang was first introduced, international SEO was primarily treated as a technical implementation challenge, ensuring search engines understood which language or regional version of a page to serve.

However, search engines now increasingly evaluate:

  • Regional search intent
  • Local terminology
  • Commercial intent
  • User expectations
  • Market-specific conversion behaviour

Therefore, businesses shouldn’t create separate locale pages simply because language variations exist. Instead, separate locale versions should generally only exist where there are meaningful differences in:

  • Products or services
  • Pricing or currency
  • Shipping availability
  • Legal requirements
  • Terminology
  • Cultural messaging
  • Search behaviour

For example, users in the US may search for “cell phone plans”, while users in the UK may search for “mobile contracts”, despite both audiences speaking English.

This shift has important implications for hreflang strategy, locale architecture, and regional SEO within a single country. While this example above demonstrates differences in the same language across multiple countries, it also applies to singular countries with multiple languages like China, South Africa, or Canada.

Language optimisation within a single country

One of the biggest opportunities for single-country language optimisation is America, due to the vast number of people who speak Spanish as a first language.

There are over 40 million people in the United States who speak Spanish as their primary language, representing around 12% of the total population, and the state of New Mexico has Spanish declared as the official language.

To put that into perspective, if all Spanish speakers in the US moved to Europe and formed their own country, it would rank as the ninth largest in Europe by population.

Regional variations in country codes

When implementing hreflang and optimising your website correctly for international SEO, it’s important to use the correct ISO country and language codes, as well as regional variants.

That being said, a single language such as Spanish can be quite complex, as the below table shows:

Language Code Language Code Meaning
es-419 Spanish as used in Latin America and the Caribbean
es-us Spanish for the United States
es Spanish
es-mx Spanish as used in Mexico
es-xl Spanish as used in Latin America
es-es Spanish – Spanish
es-ar Spanish as used in Argentina
es-pe Spanish as used in Peru
es-la Spanish as used in Lao
es-co Spanish as used in Colombia
es-do Spanish as used in the Dominican Republic
es-ec Spanish as used in Ecuador

These variations all visited a single American website, which targets Mexican customers living in the United States.

Santa Fe, New Mexico has a Spanish speaking population of 47.82%

Accounting for regional variations (the company is based in California, which has a Spanish speaking population of around 28%), it shows optimising for just “es” within the langtag might not always be the best solution for optimisation, as this website’s primary source of traffic was coming from users with browser language settings of es-419.

Langtags, regional subtags, variants and extensions

A language tag, or langtag, consists of a number of variables, including:

  • language (“en”, “es”, “zh”, or a registered value)
  • script (“Latn”, “Cyrl”, or other ISO 15924 codes)
  • region (ISO 3166 codes, or UN M.49 codes)
  • variant (such as “guoyu”, “Latn”, “Cyrl”)
  • extension (single letter followed by additional subtags)

Region subtags are mostly based on ISO 3166-1 codes and can indicate the country, or regional variation.

The region code can also include UN M.49 region codes (such as the 419 in es-419).

UN M.49 codes (United Nations M.49 codes) cover larger geographical areas and can provide an alternative to a conflict, where an ISO 3166 could be reassigned in the registry.

ISO 3166-1 does in fact require UN M.49 to define what is, and isn’t a geographical area (country or region), worthy of its own code.

This means the variations for language targeting can be expanded from the traditional “es” and “es-419”, to be more specific and targeted with HREFLANG implementations:

Tag Form Meaning
en language English
pt-BR language-region Portuguese as used in Brazil
es-419 language-region (UN M.49) Spanish as used in Central and South America
de-CH-1901 language-region-variant German as used in Switzerland, orthography of 1901
ru-Cyrl language-script Russian as written in Cyrillic
ru-Cyrl-CS language-script-region Russian as written in Cyrillic as used in Serbia and Montenegro
sl-Latn-IT-rozaj language-script-region-variant Slovenian as written in Latin as used in Italy, Resian dialect

Constructing language tags

When constructing language tags, you should follow the below format:

{language}-{extlangtag}-{script}-{region}-{variant}-{extension}

This is an important practice in larger countries such as Russia or China, where dialects can vary greatly.

Because of how Yandex works in ranking and forming search results pages (personalised for users), if you’re only targeting specific population areas, consider dialects as a part of your strategy for more focused targeting. That is, unless you’re willing to pay for air shipping to Khabarovsk or Vladivostok from Western Europe.

How specific should hreflang targeting be?

While reaching your target market is a good thing, and enables you to reach the users you want, the more targeted you go with hreflang targeting, the less matches you have with general browser and language settings.

For example, de will match with de, de-CH, de-CH-1901, de-CH-1996, de-AT, de-DE, de-1901, de-AT-1901; but de-CH will only match de-CH, de-CH-1901, de-CH-1996.

This is where business intelligence and aims need to play an important role. Being specific and targeting Swiss German means that the content will not match “just” German and Austrian German.

These language codes are not only important for just getting hreflang correct, but also for other technical aspects such as specifying the language in the server header, or in the HTML lang tag.

Simpler hreflang structures are often better

Although hreflang supports highly granular locale combinations, more specific targeting is not always the best SEO solution.

In practice, overly complex hreflang structures can create:

  • Implementation errors
  • Crawl inefficiencies
  • Weaker canonical consolidation
  • Increased maintenance overhead
  • Reduced scalability

For most websites, language-region targeting, such as by using the below examples, is usually sufficient:

  • en-gb
  • en-us
  • fr-ca
  • es-mx

More advanced locale variants should usually only be implemented where there is a clear technical, legal, linguistic, or commercial requirement.

When not to create separate locale pages

One of the most common international SEO mistakes is over-localisation – creating large numbers of regional pages with little or no meaningful differentiation.

Although hreflang supports highly specific locale targeting, this does not mean every language or regional variation should exist as a separate URL.

Creating unnecessary locale variants can lead to:

  • Duplicate or near-duplicate content
  • Diluted ranking signals
  • Crawl inefficiencies
  • Increased maintenance overhead
  • Canonicalisation conflicts
  • Weaker internal linking equity

For example, creating separate pages for minor spelling differences or near-identical service pages rarely provides meaningful SEO benefit.

Instead, separate locale pages should only exist where there are genuine differences in:

  • User intent
  • Terminology
  • Services
  • Fulfilment
  • Pricing
  • Legal requirements
  • Regional conversion behaviour

In many cases, regional SEO within a country is better handled through local landing pages and local SEO signals rather than additional hreflang variants.

Common hreflang misconceptions

A common misconception is that hreflang can be used to target regions within a single country, such as states, counties, provinces, or cities. However, Google does not support sub-country regional targeting in hreflang.

For example, the following values are not valid hreflang annotations:

  • en-us-california
  • en-gb-london
  • fr-ca-quebec

Instead, regional SEO within a country should typically be handled through:

For example:

  • /en-us/
  • /en-us/california/
  • /en-us/new-mexico/

In this structure, the national locale is handled through hreflang, while regional targeting is handled through local SEO.

This distinction is increasingly important because search engines now evaluate local intent and entity relevance far more aggressively than when hreflang was first introduced.

Canonical tags and hreflang

Another common implementation mistake in international SEO is creating conflicting canonical and hreflang signals.

Each locale page should self-canonicalise, and reference alternate locale versions via hreflang.

For example:

  • /en-gb/ canonicalises to /en-gb/
  • /en-us/ canonicalises to /en-us/

Locale pages should not canonicalise to a single “master” international page, as this can cause search engines to ignore or devalue hreflang annotations.

Incorrect canonicalisation remains one of the most common causes of hreflang implementation failure on enterprise websites.

Search intent matters more than language alone

While technical proficiency is important, modern international SEO goes beyond just translating languages.

Search engines increasingly evaluate regional search intent, terminology, and user expectations.

For example:

  • “trainers” vs “sneakers”
  • “holiday” vs “vacation”
  • “mobile contracts” vs “cell phone plans”

Although audiences may technically share the same language, their search behaviour and commercial expectations can differ significantly.

Instead of simply translating content, successful international SEO therefore requires localisation of:

  • Keyword targeting
  • Messaging
  • Calls-to-action
  • Product terminology
  • Conversion strategy

This is particularly important when targeting regions that share the same language but differ culturally or commercially.

Key takeaway: modern international SEO requires more than just hreflang

Correct use of hreflang remains an important international SEO signal, but effective localisation now requires balancing:

  • Technical implementation
  • Search intent
  • Local SEO
  • Regional user expectations
  • Commercial differentiation

Rather than relying on language targeting alone, successful international SEO strategies increasingly combine:

  • hreflang implementation
  • Local landing pages
  • Entity SEO
  • Structured data
  • Regional keyword research
  • Culturally adapted messaging

For most websites, the strongest approach is to use hreflang at the language-country level while handling regional targeting within a country through local SEO and localised content strategies.

Let SALT.agency help with your international SEO strategy

At SALT.agency, we help businesses develop scalable international SEO strategies that align with both search engine best practices and real user behaviour.

Get in touch to discuss your international SEO strategy and discover how we can help you improve visibility across languages, regions and markets.