Vaishnavam is a tradition of Hinduism, distinguished from other schools by its worship of Vishnu, or his associated Avatars such as Rama and Krishna, as the original and supreme God This worship in different perspectives or historical traditions addresses God under the names of Narayana, Krishna, Vasudeva or more often "Vishnu", and their associated avatars. Its beliefs and practices, especially the concepts of Bhakti and Bhakti Yoga, are based largely on the Upanishads, and associated with the Vedas and Puranic texts such as the Bhagavad Gita, and the Padma, Vishnu and Bhagavata Puranas.
The "Sataari" placed on the heads of all the devotees in Vishnu temples is supposed to be Nammalwar himself. All other Alwars are his limbs as brought out in the following invocatory verse:
“Bhootam Saraschya, mahadaavya Bhattanatha
Sri Bhakti sara kulashekhara yogi vahaan
Bhakataangri-renu parakala yateendra mishran,
Srimat paraangusa munim pranatosmi Nityam."
It was Sri Rangathaswamy of Sri Rangam who fondly referred to "Sadagopan" as Nammalwar (meaning, my devotee).
After this era, a gap of more than 600 years fell in the path of Vaishnava Bhakthi while religions like Jainism, Saivism etc seemed to grow.
In the ninth century, when the Divya Prabhandam, composed by all the Alwars was lost to human memeory, through yogic contact with Nammazhwar, Sriman Nadhamunigal resuscitated all the paasurams(verses) and systematized their singing at the Vishnu Temples. The great Ramanuja fostered this practice universally. He wrote 'Sri Bhashya' keeping the Sri-Sukthis of Nammalwar in mind. Manavala maamunigal and Vedanta desikar, by their compositions and discourses, gave the pride of place - Thiruvaimozhi occupies in Sri Vaishnavam.