U.S. investors often avoid Russian stocks due to the political risks, sanctions, and currency issues associated with the once-hot emerging market. But despite those challenges, there's one Russian growth stock that doubled over the past two years -- Yandex (NASDAQ:YNDX), which created the country's top search engine.

But looking ahead, I think Yandex still has plenty of room to run. These are the top five reasons investors should consider buying "Russia's Google" as a long-term investment.

St. Basil's Cathedral, Moscow.

Image source: Getty Images.

1. It's beating Google

Between March 2017 and March 2018, Alphabet's (NASDAQ:GOOG) (NASDAQ:GOOGL) share of the Russian search market, via Google, slid from 48% to 43% according to StatCounter. During the same period, Yandex's share rose from 47% to 54%.

Yandex controls 58% of the desktop search market, 46% of the tablet market, and 45% of the smartphone market. Google is the preferred search engine on 37% of desktops, 52% of tablets, and 54% of smartphones.

Yandex's lead relies heavily on the shrinking desktop market, but its 45% share of the smartphone market represents a huge jump from 29% last March. Meanwhile, Google's 54% share represents a big drop from its 68% share a year earlier.

2. Its ecosystem is expanding

Like Google, Yandex is expanding its ecosystem beyond its core search engine. It offers email and cloud storage services, a ride-hailing and food delivery service called Yandex.Taxi (which is combined with Uber's services via a joint venture), a voice-enabled virtual assistant called Alice, and the Zen AI-powered recommendations platform.

It's also testing a self-driving car, and recently partnered with Russia's top bank, Sberbank, to launch an e-commerce joint venture. It also lets users buy products online at about 76,000 stores with its Yandex.Checkout payments platform. On the streaming media front, its homepage is integrated with 43 TV channels and content from 30 on-demand video providers.

Back in 2014, Yandex launched a firmware update called Yandex.kit that replaced all of Google's apps on Android phones with its own. It subsequently partnered with a wide range of smartphone makers to pre-install its services. That partly explains why Yandex is beating Google in Russia.

3. The Russian government distrusts Google

Yandex is also pulling ahead because the Russian government distrusts Google. In 2015, it threatened to ban Google over its refusal to turn over personal data about bloggers. Google moved some of its servers to Russia that year to comply with a controversial law that requires the personal data of Russian citizens to remain within the country.

Yandex's mobile app.

Yandex's mobile app. Image source: Google Play.

A recent internet ban aimed at the encrypted messaging app Telegram also blocked websites hosted on Google and Amazon servers. Yandex's sites weren't affected.

It's unlikely that Google will voluntarily leave Russia as it did China in 2010, but there's always the risk that the government could abruptly ban its services. If that happens, Yandex -- like Baidu in China -- would quickly conquer the market.

4. A growing internet market

Russia has an internet penetration rate of 71%. That's the highest rate out of the BRIC nations, but it's considerably lower than the U.S.'s penetration rate of 89%. As Russia's economy gradually recovers, aided by stabilizing oil prices and forex rates, that rate will likely rise and support the growth of Yandex's online ecosystem.

5. Impressive growth rates at a reasonable valuation

Yandex's revenue rose 24% to $1.63 billion last year, while its net income grew 28% to $150 million. Yandex posted triple-digit sales growth in two segments -- Yandex.Taxi and Experiments (non-core media, data, and overseas businesses) -- as its search/portal and classifieds revenues grew by the double digits.

Wall Street expects Yandex's growth to accelerate, with 28% sales growth and 40% earnings growth this year followed by 25% sales growth and 44% earnings growth next year. Those are impressive growth rates for a stock that trades at 31 times this year's earnings and 21 times next year's earnings.

The key takeaway

Yandex isn't a stock for queasy investors, since it could easily be rocked by political or economic tensions in Russia. However, I think it represents a solid growth play in a country dominated by cyclical commodity stocks, and that its double-digit sales and earnings growth should continue for the foreseeable future.