Then the mighty-armed Bhimasena, at the command of the king, sent out messengers to the great kings of the Earth. Those best of kings, came to the Horse-sacrifice of the Kuru monarch for doing what was agreeable to him. And they brought many gems with them and many female slaves and horses and weapons.
And later from the same chapter:
Many sacrificial stakes also were set up, made, according to the directions of the scriptures of wood, and adorned with gold. Endued with great effulgence, these were duly planted and dedicated (with scriptural Mantras). The king saw all animals, again, which belong to land and all those which belong to water, collected there on the occasion. And they also beheld many kine and many buffaloes and many old women, and many aquatic animals, many beasts of prey and many species of birds, and many specimens of viviparous and oviparous creatures, and many that are filth-born, and many belonging to the vegetable kingdom, and many animals and plants that live or grow on mountains. Beholding the sacrificial compound thus adorned with animals and kine and corn, the invited kings became filled with wonder.
Large heaps of costly sweet-meats were kept ready for both the Brahmanas and the Vaisyas. And when the feeding was over of a hundred thousand Brahmanas, drums and cymbals were beat. And so large was the number fed that the sounds of drums and cymbals were repeatedly heard, indeed, from day to day those sounds continued. Thus was performed that sacrifice of king Yudhishthira of great intelligence.
Were those women really sacrificed during Yudhiṣṭhira's aśvamedha-yajña or were they just witness to it?