After hearing Chen Sen's new theory, Ling Hao became slightly dazed because he understood what Chen Sen meant by 'those people'. The Ling family and the Chen family were both at the top of China's most powerful families and being the two future leaders of these families, both of them definitely know more things than the average person.
Those people included the ancient clans of China and also all the well-known but concealed sects. There were many scary possibilities, as some were above the ordinary authorities of the world. These people were not afraid of weapons and did not come to compete for power. Instead, they lived quietly and only focused on their training so as to improve their abilities.
These people were mysterious and unapproachable by the usual commoner. While access to them was limited, they were definitely present.