Primary schoolchildren are set to learn about Mexico up to the 1500s
A row has erupted in Mexico after the government distributed a history textbook to primary schools which makes no mention of the Spanish conquest.
The chronology of the text neatly avoids the issue by ending before the Spanish arrived in the early 1500s.
Some opposition figures have seized on what they see as a calculated omission.
The arrival of the conquistadors resulted in the deaths of hundreds of thousands of indigenous people and the colonisation of Mexico.
On Monday, as 25 million children started the new school term, the government has found itself in the middle of a controversy it apparently did not see coming, says the BBC's Stephen Gibbs in Mexico City.
The new history textbook, published and distributed free by the education ministry, omits what historians agree was one of the most important eras in the country's history - the arrival of the Spanish led by Hernan Cortes in 1519 that led ultimately to colonisation until Mexico gained independence in 1821.
Some opposition politicians have accused the conservative government of President Felipe Calderon of deliberately discouraging a critical analysis of the conquest.
The government is even accused of being closer to the Spanish conquerors than to Mexico's indigenous population.
The textbook was "an attack on the nation's identity", said the president of the culture committee of the chamber of deputies, Alfonso Suarez del Real, from the opposition PRD party.
But the country's assistant education secretary, Fernando Gonzalez, said criticism was not warranted.
The Spanish conquest should and would be studied in depth by secondary school pupils, he said.
Mr Gonzalez added that the school history textbooks were "continually being improved".