Nandinathar wrote Nandikeshvara Kasika which propounded the philosophical system of Saiva Siddhantha. His disciple Thirumular wrote Thirumanthiram 250BC to spread Shaivam in Tamil land. 

Thevaram, Shaiva hymns, were sung by 63 Shaivaite saints called Nayanmars to propagate Shaivism.

Prominent 3 Nayanmars were 

1. Thirugnana Sambanthar (Sambanthar )7AD
   
2. Thirunavukkarasar (Appar) 7AD
   
3. Sundaramoorthy Nayanar (Sundarar) 8AD
   

These three along with one other saint Manikkavasagar, who wrote Thiruvasakam are known as NAALVAR (The Four). 

The story of the 63 Nayanmars was written by Sekkizhar 1150AD known as Periyapuranam. 

Nambi Andar Nambi of 11AD compiled 18,316 thevaraam slokams and Periyapuranam in 12 Thirumurai, called Paniru Thirumurai. 

1300 years after Saint Tirumular, dualistic interpretations were put forth by Meykanda Devar in Sivajnana Bodham. 

Lineage of santhAna kuravargaL Gurus

1. Paranchodhi Munivar, 
   
2. Meykanda Devar, 
   
3. Arunandhi Shivam, 
   
4. Marainyana Sambandhar, 
   
5. Umapathi Shivachchariyar 
   

63 Nayanmars 

1. Sundaramurthi Nayanar
   
2. Thiru Neelakanta Nayanar
   
3. Iyarpahai Nayanar
   
4. Ilayankudi Mara Nayanar
   
5. Maiporul Nayanar
   
6. Viralminda Nayanar
   
7. Amaraneedi Nayanar
   
8. Eripatha Nayanar
   
9. Enadinatha Nayanar
   
10. Kannappa Nayanar
    
11. Kungiliya Kalaya Nayanar
    
12. Manakanchara Nayanar
    
13. Arivattaya Nayanar
    
14. Anaya Nayanar
    
15. Murthi Nayanar
    
16. Muruga Nayanar
    
17. Rudra Pasupathi Nayanar
    
18. Thiru NalaiPovar Nayanar
    
19. Thiru Kuripputhonda Nayanar
    
20. Chandesvara Nayanar
    
21. Thirunavukkarasar Nayanar
    
22. Kulacchirai Nayanar
    
23. Perumizhalai Kurumba Nayanar
    
24. Karaikal Ammaiyar
    
25. Appuddi Nayanar
    
26. Thiruneelanakka Nayanar
    
27. Nami Nandi Adigal
    
28. Thiru Jnana Sambandar
    
29. Eyarkon Kalikama Nayanar
    
30. Thiru Mula Nayanar
    
31. Dandi Adigal Nayanar
    
32. Murkha Nayanar
    
33. Somasira Nayanar
    
34. Sakkiya Nayanar
    
35. Sirappuli Nayanar
    
36. Siruthonda Nayanar
    
37. Cheraman Perumal Nayanar
    
38. Gananatha Nayanar
    
39. Kootruva Nayanar
    
40. Pugal Chola Nayanar
    
41. Narasinga Muniyaraiyar
    
42. Adipattha Nayanar
    
43. Kalikamba Nayanar
    
44. Kalia Nayanar
    
45. Satti Nayanar
    
46. Aiyadigal Kadavarkon Nayanar
    
47. Kanampulla Nayanar
    
48. Kari Nayanar
    
49. Ninra Seer Nedumara Nayanar
    
50. Mangayarkarasiyar
    
51. Vayilar Nayanar
    
52. Munaiyaduvar Nayanar
    
53. Kazharsinga Nayanar
    
54. Seruthunai Nayanar
    
55. Idangazhi Nayanar
    
56. Pugazh Tunai Nayanar
    
57. Kotpuli Nayanar
    
58. Pusalar Nayanar
    
59. Nesa Nayanar
    
60. Kochengat Chola Nayanar
    
61. Thiru Neelakanta Yazhpanar
    
62. Sadaya Nayanar
    
63. Isaijnaniyar 
    

Saiva Siddhanta philosophy

The central doctrine of the Saiva Siddhanta philosophy is

Shiva (Parama Athma) is the Supreme Reality (Nirguna Brahm)
Individual soul (jiva athma) is of the same essence as Shiva, but not identical. 

(Same but not equal)

• Pati (God)
  
• Pasu (soul)
  
• Pasa (the bonds) and 
  
• The thirty-six Tattvas or principles which constitute the world, are all real. 
  

Characteristics of the Supreme Reality:

The Supreme Reality(Nirguna Brahm) is called Shiva. 

That Shiva is infinite consciousness, eternal, changeless, formless, independent, omnipresent, omnipotent, omniscient, one without a second, beginningless, causeless, taintless, self-existent, ever free, ever pure, perfect, timeless. Shiva is infinite bliss and infinite intelligence. Shiva is free from defects, the all-doer, the all-knower.  Shiva is Love. Shiva is the saviour and Guru. Shiva is engaged in freeing the souls from the thraldom of matter. Shiva assumes the form of a Guru out of Shiva's intense love for mankind. Shiva liberates the individual souls from their fetters or bonds. 

Shiva Activities are: 

1. Creation
   
2. Preservation
   
3. Destruction
   
4. Veiling
   
5. Grace
   

 These, separately considered, are the activities of 

1. Brahma
   
2. Vishnu
   
3. Rudra
   
4. Maheshwara
   
5. SadaShiva
   

Shiva, Shakti and Maya(Illusion): 

Shiva pervades the whole world by Shakti and is the conscious energy of the Shiva, that works through Shakti. 

• Shiva is the first cause of the world. 
  
• Shakti is the instrumental cause. 
  
• Maya is the material cause. 
  

Shakti is not the material cause of the universe, because Shakti is of the nature of consciousness (Chaitanya). 

• Shiva is pure consciousness
  
• matter is pure unconsciousness
  
• Shakti is the intermediate link between the two. 
  

Shakti is the reflex of Shiva. Both Shiva and Shakti has no independent existence.

 Like sun and its rays Shiva and Shakti co-exists.