The rankings are based entirely on national team results. Every country in there has a national team that takes part in the World Championship. There are other countries in the IIHF (like Thailand or Liechtenstain or whoever) which currently or in the last 4 years haven't had a national team competing.
They compete, but not in the World Championship structure.
If anyone is interested I keep a ranking including IIHF sanctioned or endorsed tournaments that run beneath the World Championship structure. In the last 4 years these include:
IIHF Challenge Cup of Asia: 2010, 2011, 2012, 2013;
Asian Winter Games: 2011;
Gulf Cup: 2010, 2012;
It affects the bottom end of the rankings as follows:
40 Turkey
41 South Africa
42 North Korea
43 Ireland
44 Luxembourg
45 Greece
46 United Arab Emirates
47 Mongolia
48 Chinese Taipei
49 Thailand
50 Kuwait
51 Malaysia
52 Hong Kong
53 Georgia
54 Macau
55 India
56 Kyrgyzstan
57 Bahrain
58 Singapore
59 Oman
60 Saudi Arabia
In early March a Pan-American tournament will be added to this as well played in Mexico.
Also for sure Argentina, Qatar & Bosnia have played exhibition games over that period as a national team as well.