someone is claiming to be original owner of my land

I bought an agricultural land in Delhi in an unauthorized colony in 2004 from a property dealer on GPA, Sale deed and Will and all these documents are notary attested and registered under sub registrar as well and I am living here since that time only. Suddenly someone is claiming this land and he filed a case on this land in SDM court Delhi in Dec 2012, saying that somebody sold this land on forged documents. We got a notice from SDM court to appear in SDM court in Jan 2014. On approaching a lawyer he said one can not file the case in SDM Court after such a long time period because you are living in this house since 2004 and the person who is claiming to be the owner of this land has filed this case in SDM court in Dec 2012. He said one can file the case in SDM court within 3 years from the construction took place. And he assured us that do not worry this case will get dismissed from the SDM court on this ground and you are safe. But I am confused about the fate of this case. Kindly Guide as I do not know anything about Property Laws of Delhi.