No & No. India was very rich before foreign invasion. So much so that europeans were clamoring to find a sea route that they ended up finding a new continent , called the natives 'Indians' and plundered the new land.
India before invasions was never a united nation in the way the word 'nation' is interpretted.
It is difficult to define the concepts behind India in terms used by Europeans. "Nation" is a European concept of political division. Usually Europe was governed by groups that were similar based on language (French , English, Spanish) or language/ religion combinations (Germany, Austria). European nations like Switzerland are an exception to this.
In the middle east & Africa , it was mostly tribal alliances. Arab speaking nations were divided into multiple nations by Europeans after the world war & oil discovery. Concept of nation was imposed on Africa & South America , based on colonial territories held. In each of these cases , heterogeneous communities could not get along and this led to nation states.
Bharat varsha is very unique in the world w.r.t to the tolerance to people of different views and faiths. This is true to this date. By and large Hindus accepted Jains , Buddhists , atheists , Christians etc.. There was never a sustained inquisitions , pogrom's or jihads carried out by the state on people with differing cultural practice. Mohammadism was opposed mainly due to the brutality and violence that accompanied by its adherents.
What defines India as a cohesive group is adherence to Hinduism and resulting tolerance.
This will be the case even going forward. This is where India will be unique and thrive into the future, while balkans , USSR or even Canada - think of french canada - fail. We have to thank our Rishi's & Vedas for imbibing "ekam sat viprah bahudha vadanti" as part of our culture.
If we go by the current European notion of "nation" , India was always an aggregate of different nations . Every now and then , some dynasties (Mauryas, Magadhs , Guptas , Mughals etc..) asserted dominance and made other nations vassals. During those brief periods , the empires resembled the present day India.