Samsung Electronics Co. (005930), the largest smartphone maker, posted the lowest sales at its mobile-phone business in five quarters as Chinese producers gain in emerging markets with cheaper, feature-packed devices.

Revenue at the mobile division, the company’s biggest business, fell to 32.4 trillion won ($31 billion) in the three months ended March, the lowest since the quarter ended Dec. 31, 2012, Samsung said today. The Suwon, South Korea-based company’s share of the global smartphone market fell for the first time in four years, according to Strategy Analytics.

Samsung has been buying market share, which isn’t a sustainable model. Their powerful marketing led to massive profits — the only profitable Android smartphone maker, in fact — but leaves them vulnerable to lower-cost manufacturers without massive spiff budgets.

I don’t know if this was just one so-so quarter, or the beginning of the beginning of the end for Samsung’s Android dominance. A year from now and we might all know for sure.