:The problem is not that OECD's data is unreliable but that those claims are not actually supported by the referenced pages.  The TL3 data is used for Ulsan's "the second richest city" claim.  However, The TL3 obviously is not city level division but provincial and metropolitan city level division in South Korea and prefectural level division in Japan. As noted above, several cities in Japan have higher GDP per capita than Ulsan. The TL3 data also shows that Gyeongsangnam province's GDP per capita is 20,737 USD.  Also note that those data cover South Korea and Japan only so cannot be used to assert their relative wealth "in East Asia". Based on this, I removed those claims.