The Buddha saw them in a vision coming towards Savatthi and intuited that they had the capacity to attain enlightenment. He therefore went and waited for them under a large banyan tree on the bank of the river.
Great Kappina and his ministers came by the river and saw a marvelous figure under a banyan tree. The Buddha was radiating six colorful rays from his body as they approached and bowed. He then delivered a sutra to the group. And as they listened to the discourse, the king and all his ministers realized the Dharma (stream entry) and became members of the Sangha.
Sangha can mean the instructed "Monastic Order" or the accomplished "Noble Order." They had just become ennobled members of the "accomplished community of Buddhist disciples" in reaching stream entry by penetrating the Four Noble Truths.
Lives happily and serene in mind
For the wise ever in that Truth delight
Revealed by the Noble Ones.