How come china and india are still " developing nations " or 3rd world after 5000- years. do you know?

They're not third world "after 5000 years".  First off, "third world" is a politicial designation of the countries between the US and its allies and the Soviets and its allies during the Cold War, although it's often used as a synonym for "developing world".

Second, and more importantly, India and China as developing countries is relatively recent, historically.  It's only in the last 200 years or so that the West pulled decisively away from the East as industrialization ramped up.  China used to be the developed world.  It was much much richer than Europe until the industrial revolution happened. 

The reason that they're developing now and not developed is largely due to colonialism.  India experienced it more directly, having been under British rule wholly, or in part, for 200 years.  The British ran India for their own benefit, not that of India.  And that impoverished the country.  Similar things happened with China.  They were not directly ruled by Western power (except for a few places like Hong Kong and Macau) but were sitll subjected to colonialism which robbed them of their wealth.