Simplify the following text for a Grade 6 native English-speaking person.
Original: This would later become known as the Parsley Massacre from the shibboleth that Trujillo had his soldiers apply to determine whether or not those living on the border were native Dominicans who spoke Spanish fluently . Soldiers would hold up a sprig of parsley , ask `` What is this ? ''
Simplified: This would later become known as the Parsley Massacre .