Oppo may be little-known in the West, but the Chinese smartphone company has outsold everyone else across in China over 2016.

Analyst firm IDC reports that Oppo more than doubled its shipment volumes over the year prior, to clinch the top spot. It beat other strong Chinese contenders like Xiaomi and Huawei -- as well as Apple, which posted its first decline in China.

The Chinese smartphone makers in the top five list have taken up a larger slice of the market, as their share grew from 46 percent in 2015 to 57 percent in 2016:

Oppo and vivo -- both in the top-five list -- are owned by BBK, a Guangzhou-based company, which is aggressively targeting China, India and Southeast Asia.

IDC said consumers continue to seek phone upgrades, and this was met with aggressive marketing by Oppo and vivo, which have been targeting the massive mid-market in China.

Despite the year-on-year decline in sales for Apple -- the first since the company launched the iPhone in China in 2009 -- IDC believes that that Chinese smartphone makers have yet to eat away at Apple's market share, with most Apple users reportedly holding out for a new iPhone rumoured to be set for the iPhone's 10th anniversary.

But Apple has an increasingly tough time in the world's biggest smartphone market. Both Oppo and vivo both have nearly 31.6 percent market share, and have successfully pushed out Samsung from the list of top five smartphone makers tracked by the IDC.

Samsung was the top performer with a 24.6 percent market share in 2015, but was scrubbed from the list following its disastrous showing with the Galaxy Note7.