Simplify the following text for a Grade 6 native English-speaking person.
Original: On January 19 , 1981 , after thirteen straight hours of negotiation , all parties present signed the first Concorde Agreement , named after the plaza in Paris where the discussions took place .
Simplified: On 19 January 1981 , the first Concorde Agreement was signed . The agreement was named after the plaza in Paris where the discussions took place .