This map, found on an intriguing site called strangemaps.com (found via Steven Levitt and Stephen Dubner’s Freakonomics Blog), shows the "potential scope" of China’s spheres of influence, with one line showing its reach as a "regionally dominant Greater China" and one as "a global power", along with arrows indicating potential power conflicts. It seems to be fairly current (though the site’s owner apparently can’t remember where it came from originally), and interestingly shows Chinese influence projecting as far west as the Caspian Sea and as far south as the Straits of Malacca:
The "regional" map shows China’s sphere of influence extending over Mongolia, North Korea, Taiwan, the Indochinese states of Vietnam, Cambodia and Laos, but also Thailand, Burma/Myanmar and the continental part of Malaysia. A remarkable addition in the west is Pakistan, giving China almost immediate access to the Persian Gulf.
The "global" map sees China’s influence extending beyond the aforementioned countries to most of the former Soviet Central Asian ‘stans’ (except Turkmenistan), part of Afghanistan, the whole of Indonesia, the rest of Malaysia, the Philippines, South Korea and significant parts of the Russian Far East.
In both scenarios, friction remains possible with the two other regional powers that remain independent, India and Japan.
The site has scores of other off-beat and/or thought-provoking maps, including quite a few more China-related ones. It has also inspired this one of the USA color-coded to match the major world economies (China, Germany, Japan and the UK) with clusters of states that collectively have a similar GDP. So China’s economy is roughly equivalent to the west coast, Alaska, Hawaii and Nevada, while Japan’s takes up New England plus the entire heartland, including Texas. Germany gets the South, while the UK gets the mid-Atlantic: