Asia consists of following prefixes:
(in red colour not confirmed by qsl) 
25 Japan 
48 Saudi Arabia 
57 India 
60 Hong Kong 
86 Nepal 
94 United Arab Emirates
95 Mongolia
97 Israel
98 Singapore
100 Republic of Korea
102 Kuwait
110 Cyprus 
111 Jordan
112 Lebanon 
113 West Malaysia 
114 Pakistan
115 Qatar
149 Lakshadweep Is.
150 Bahrain
151 Iraq
152 Maldives
153 Thailand 
154 Iran
155 Taiwan
177 Sri Lanka
181 Syria 
202 Bhutan
203 China
234 Afghanistan
236 Bangladesh 
237 Myanmar
238 Cambodia 
239 Laos
240 Macao 
241 Spratly Is. 
242 Vietnam
253 Andaman & Nicobar Is.
281 Ogasawara
291 UK Sov. Base Areas on Cyprus
292 Abu-Ail & Jabal-At-Tair
301 Armenia
302 Asiatic Russia
303 Azerbaijan
306 Georgia
308 Kazakhstan
309 Kyrgyzstan
313 Tajikistan
314 Turkmenistan
316 Uzbekistan 
323 Yemen 
334 DPR of Korea 
335 Pratas I.
336 Scarborough Reef
340 Palestine